diff --git a/20220321/Operating_system_placement-de.pdf b/20220321/Operating_system_placement-de.pdf
new file mode 120000
index 0000000000000000000000000000000000000000..0ac467095a599f2fdacc118bc84feb070a03d2d5
--- /dev/null
+++ b/20220321/Operating_system_placement-de.pdf
@@ -0,0 +1 @@
+../common/Operating_system_placement-de.pdf
\ No newline at end of file
diff --git a/20220404/Makefile b/20220404/Makefile
new file mode 120000
index 0000000000000000000000000000000000000000..f6b6055dee93f47bde83b09e1618e38152ac699f
--- /dev/null
+++ b/20220404/Makefile
@@ -0,0 +1 @@
+Makefile-modules-1
\ No newline at end of file
diff --git a/20220404/Makefile-1 b/20220404/Makefile-1
new file mode 100644
index 0000000000000000000000000000000000000000..bfc1b10a929f22a8c2f4f0cf0368c78db14ad0b0
--- /dev/null
+++ b/20220404/Makefile-1
@@ -0,0 +1,8 @@
+philosophy: philosophy.o answer.o
+ gcc philosophy.o answer.o -o philosophy
+
+answer.o: answer.c answer.h
+ gcc -Wall -O answer.c -c
+
+philosophy.o: philosophy.c answer.h
+ gcc -Wall -O philosophy.c -c
diff --git a/20220404/Makefile-2 b/20220404/Makefile-2
new file mode 100644
index 0000000000000000000000000000000000000000..60aab7c7d51b28879c41e8590ab422e9edfadee5
--- /dev/null
+++ b/20220404/Makefile-2
@@ -0,0 +1,16 @@
+TARGET = philosophy
+OBJECTS = philosophy.o answer.o
+HEADERS = answer.h
+CFLAGS = -Wall -O
+
+$(TARGET): $(OBJECTS)
+ gcc $(OBJECTS) -o $(TARGET)
+
+answer.o: answer.c $(HEADERS)
+ gcc $(CFLAGS) answer.c -c
+
+philosophy.o: philosophy.c $(HEADERS)
+ gcc $(CFLAGS) philosophy.c -c
+
+clean:
+ rm -f $(OBJECTS) $(TARGET)
diff --git a/20220404/Makefile-3 b/20220404/Makefile-3
new file mode 100644
index 0000000000000000000000000000000000000000..0ac355bfddfd237fe0f1b5062c5a242ab0d3e97e
--- /dev/null
+++ b/20220404/Makefile-3
@@ -0,0 +1,13 @@
+TARGET = philosophy
+OBJECTS = philosophy.o answer.o
+HEADERS = answer.h
+CFLAGS = -Wall -O
+
+$(TARGET): $(OBJECTS)
+ gcc $(OBJECTS) -o $(TARGET)
+
+%.o: %.c $(HEADERS)
+ gcc $(CFLAGS) $< -c
+
+clean:
+ rm -f $(OBJECTS) $(TARGET)
diff --git a/20220404/Makefile-modules-1 b/20220404/Makefile-modules-1
new file mode 100644
index 0000000000000000000000000000000000000000..817bd62fcb708a904341be771524c0fa2878c5da
--- /dev/null
+++ b/20220404/Makefile-modules-1
@@ -0,0 +1,9 @@
+obj-m += hellomod-1.o
+obj-m += hellomod-2.o
+obj-m += chardev-1.o
+
+all:
+ make -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules
+
+clean:
+ make -C /lib/modules/$(shell uname -r)/build M=$(PWD) clean
diff --git a/20220404/answer.c b/20220404/answer.c
new file mode 100644
index 0000000000000000000000000000000000000000..e11399f0b3f482162893cbadf5db11129fdb2ef2
--- /dev/null
+++ b/20220404/answer.c
@@ -0,0 +1,6 @@
+#include "answer.h"
+
+int answer (void)
+{
+ return ANSWER;
+}
diff --git a/20220404/answer.h b/20220404/answer.h
new file mode 100644
index 0000000000000000000000000000000000000000..6632ffe85a1f2222765dc071a229b15b897339df
--- /dev/null
+++ b/20220404/answer.h
@@ -0,0 +1,3 @@
+extern int answer (void);
+
+#define ANSWER 42
diff --git a/20220404/chardev-1.c b/20220404/chardev-1.c
new file mode 100644
index 0000000000000000000000000000000000000000..17a6651a33313322de202fbcb6bbf82333c0b766
--- /dev/null
+++ b/20220404/chardev-1.c
@@ -0,0 +1,166 @@
+/*
+ * chardev.c: Creates a read-only char device that says how many times
+ * you've read from the dev file
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <asm/uaccess.h> /* for put_user */
+
+/*
+ * Prototypes - this would normally go in a .h file
+ */
+int init_module(void);
+void cleanup_module(void);
+static int device_open(struct inode *, struct file *);
+static int device_release(struct inode *, struct file *);
+static ssize_t device_read(struct file *, char *, size_t, loff_t *);
+static ssize_t device_write(struct file *, const char *, size_t, loff_t *);
+
+#define SUCCESS 0
+#define DEVICE_NAME "chardev" /* Dev name as it appears in /proc/devices */
+#define BUF_LEN 80 /* Max length of the message from the device */
+
+/*
+ * Global variables are declared as static, so are global within the file.
+ */
+
+static int Major; /* Major number assigned to our device driver */
+static int Device_Open = 0; /* Is device open?
+ * Used to prevent multiple access to device */
+static char msg[BUF_LEN]; /* The msg the device will give when asked */
+static char *msg_Ptr;
+
+static struct file_operations fops = {
+ .read = device_read,
+ .write = device_write,
+ .open = device_open,
+ .release = device_release
+};
+
+/*
+ * This function is called when the module is loaded
+ */
+int init_module(void)
+{
+ Major = register_chrdev(0, DEVICE_NAME, &fops);
+
+ if (Major < 0) {
+ printk(KERN_ALERT "Registering char device failed with %d\n", Major);
+ return Major;
+ }
+
+ printk(KERN_INFO "I was assigned major number %d. To talk to\n", Major);
+ printk(KERN_INFO "the driver, create a dev file with\n");
+ printk(KERN_INFO "'mknod /dev/%s c %d 0'.\n", DEVICE_NAME, Major);
+ printk(KERN_INFO "Try various minor numbers. Try to cat and echo to\n");
+ printk(KERN_INFO "the device file.\n");
+ printk(KERN_INFO "Remove the device file and module when done.\n");
+
+ return SUCCESS;
+}
+
+/*
+ * This function is called when the module is unloaded
+ */
+void cleanup_module(void)
+{
+ /*
+ * Unregister the device
+ */
+ unregister_chrdev(Major, DEVICE_NAME);
+}
+
+/*
+ * Methods
+ */
+
+/*
+ * Called when a process tries to open the device file, like
+ * "cat /dev/mycharfile"
+ */
+static int device_open(struct inode *inode, struct file *file)
+{
+ static int counter = 0;
+
+ if (Device_Open)
+ return -EBUSY;
+
+ Device_Open++;
+ sprintf(msg, "I already told you %d times Hello world!\n", counter++);
+ msg_Ptr = msg;
+ try_module_get(THIS_MODULE);
+
+ return SUCCESS;
+}
+
+/*
+ * Called when a process closes the device file.
+ */
+static int device_release(struct inode *inode, struct file *file)
+{
+ Device_Open--; /* We're now ready for our next caller */
+
+ /*
+ * Decrement the usage count, or else once you opened the file, you'll
+ * never get get rid of the module.
+ */
+ module_put(THIS_MODULE);
+
+ return 0;
+}
+
+/*
+ * Called when a process, which already opened the dev file, attempts to
+ * read from it.
+ */
+static ssize_t device_read(struct file *filp, /* see include/linux/fs.h */
+ char *buffer, /* buffer to fill with data */
+ size_t length, /* length of the buffer */
+ loff_t * offset)
+{
+ /*
+ * Number of bytes actually written to the buffer
+ */
+ int bytes_read = 0;
+
+ /*
+ * If we're at the end of the message,
+ * return 0 signifying end of file
+ */
+ if (*msg_Ptr == 0)
+ return 0;
+
+ /*
+ * Actually put the data into the buffer
+ */
+ while (length && *msg_Ptr) {
+
+ /*
+ * The buffer is in the user data segment, not the kernel
+ * segment so "*" assignment won't work. We have to use
+ * put_user which copies data from the kernel data segment to
+ * the user data segment.
+ */
+ put_user(*(msg_Ptr++), buffer++);
+
+ length--;
+ bytes_read++;
+ }
+
+ /*
+ * Most read functions return the number of bytes put into the buffer
+ */
+ return bytes_read;
+}
+
+/*
+ * Called when a process writes to dev file: echo "hi" > /dev/hello
+ */
+static ssize_t
+device_write(struct file *filp, const char *buff, size_t len, loff_t * off)
+{
+ printk(KERN_ALERT "Sorry, this operation isn't supported.\n");
+ return -EINVAL;
+}
diff --git a/20220404/freedos.hd b/20220404/freedos.hd
new file mode 100644
index 0000000000000000000000000000000000000000..bf24ea7697c79c81cbb1ff01ddb015a63faff730
Binary files /dev/null and b/20220404/freedos.hd differ
diff --git a/20220404/hellomod-1.c b/20220404/hellomod-1.c
new file mode 100644
index 0000000000000000000000000000000000000000..a9fef793369a4e24da98b91e1bb7c651190ceea2
--- /dev/null
+++ b/20220404/hellomod-1.c
@@ -0,0 +1,20 @@
+/*
+ * hello-1.c - The simplest kernel module.
+ */
+#include <linux/module.h> /* Needed by all modules */
+#include <linux/kernel.h> /* Needed for KERN_INFO */
+
+int init_module(void)
+{
+ printk(KERN_INFO "Hello world 1.\n");
+
+ /*
+ * A non 0 return means init_module failed; module can't be loaded.
+ */
+ return 0;
+}
+
+void cleanup_module(void)
+{
+ printk(KERN_INFO "Goodbye world 1.\n");
+}
diff --git a/20220404/hellomod-2.c b/20220404/hellomod-2.c
new file mode 100644
index 0000000000000000000000000000000000000000..a2bb30b1329f9a2997a2d6164631618635f41f4c
--- /dev/null
+++ b/20220404/hellomod-2.c
@@ -0,0 +1,22 @@
+/*
+ * hello-2.c - The simplest kernel module.
+ */
+#include <linux/module.h> /* Needed by all modules */
+#include <linux/kernel.h> /* Needed for KERN_INFO */
+
+MODULE_LICENSE("GPL");
+
+int init_module(void)
+{
+ printk(KERN_INFO "Hello world 2.\n");
+
+ /*
+ * A non 0 return means init_module failed; module can't be loaded.
+ */
+ return 0;
+}
+
+void cleanup_module(void)
+{
+ printk(KERN_INFO "Goodbye world 2.\n");
+}
diff --git a/20220404/make-1.txt b/20220404/make-1.txt
new file mode 100644
index 0000000000000000000000000000000000000000..bae6639927d6ea0b9faa07e2884b1e2b10edba15
--- /dev/null
+++ b/20220404/make-1.txt
@@ -0,0 +1,60 @@
+cassini/home/peter/bo/2022ss/bs/20220404> cat philosophy.c
+#include <stdio.h>
+#include "answer.h"
+
+int main (void)
+{
+ printf ("The answer is %d.\n", answer ());
+ return 0;
+}
+cassini/home/peter/bo/2022ss/bs/20220404> cat answer.h
+extern int answer (void);
+
+#define ANSWER 42
+cassini/home/peter/bo/2022ss/bs/20220404> cat answer.c
+#include "answer.h"
+
+int answer (void)
+{
+ return ANSWER;
+}
+cassini/home/peter/bo/2022ss/bs/20220404> gcc -Wall -O philosophy.c -o philosophy
+/usr/bin/ld: /tmp/ccjJ8ZhE.o: in function `main':
+philosophy.c:(.text+0x5): undefined reference to `answer'
+collect2: error: ld returned 1 exit status
+cassini/home/peter/bo/2022ss/bs/20220404> gcc -Wall -O philosophy.c answer.c -o philosophy
+Sie haben neue Post in /var/mail/peter.
+cassini/home/peter/bo/2022ss/bs/20220404> ./philosophy
+The answer is 42.
+cassini/home/peter/bo/2022ss/bs/20220404> gcc -Wall -O philosophy.c -c
+cassini/home/peter/bo/2022ss/bs/20220404> gcc -Wall -O answer.c -c
+cassini/home/peter/bo/2022ss/bs/20220404> ls -l philosophy.[co] answer.[co]
+-rw-r--r-- 1 peter peter 60 Dez 13 13:46 answer.c
+-rw-r--r-- 1 peter peter 1208 Apr 4 13:57 answer.o
+-rw-r--r-- 1 peter peter 117 Jan 4 2021 philosophy.c
+-rw-r--r-- 1 peter peter 1632 Apr 4 13:57 philosophy.o
+cassini/home/peter/bo/2022ss/bs/20220404> gcc philosophy.o answer.o -o philosophy
+cassini/home/peter/bo/2022ss/bs/20220404> ./philosophy
+The answer is 42.
+cassini/home/peter/bo/2022ss/bs/20220404> gcc philosophy.o -o philosophy
+/usr/bin/ld: philosophy.o: in function `main':
+philosophy.c:(.text+0x5): undefined reference to `answer'
+collect2: error: ld returned 1 exit status
+cassini/home/peter/bo/2022ss/bs/20220404> cat Makefile-1
+philosophy: philosophy.o answer.o
+ gcc philosophy.o answer.o -o philosophy
+
+answer.o: answer.c answer.h
+ gcc -Wall -O answer.c -c
+
+philosophy.o: philosophy.c answer.h
+ gcc -Wall -O philosophy.c -c
+cassini/home/peter/bo/2022ss/bs/20220404> make
+make: *** Es wurden keine Ziele angegeben und keine „make“-Steuerdatei gefunden. Schluss.
+cassini/home/peter/bo/2022ss/bs/20220404> make -f Makefile-1
+gcc philosophy.o answer.o -o philosophy
+cassini/home/peter/bo/2022ss/bs/20220404> rm *.o
+cassini/home/peter/bo/2022ss/bs/20220404> make -f Makefile-1
+gcc -Wall -O philosophy.c -c
+gcc -Wall -O answer.c -c
+gcc philosophy.o answer.o -o philosophy
diff --git a/20220404/make-2.txt b/20220404/make-2.txt
new file mode 100644
index 0000000000000000000000000000000000000000..ab38c8dd947a3c1b4c8ab3541176519d9634e261
--- /dev/null
+++ b/20220404/make-2.txt
@@ -0,0 +1,45 @@
+/*
+ * hello-1.c - The simplest kernel module.
+ */
+#include <linux/module.h> /* Needed by all modules */
+#include <linux/kernel.h> /* Needed for KERN_INFO */
+
+int init_module(void)
+{
+ printk(KERN_INFO "Hello world 1.\n");
+
+ /*
+ * A non 0 return means init_module failed; module can't be loaded.
+ */
+ return 0;
+}
+
+void cleanup_module(void)
+{
+ printk(KERN_INFO "Goodbye world 1.\n");
+}
+cassini/home/peter/bo/2022ss/bs/20220404> cat Makefile-modules-1
+obj-m += hellomod-1.o
+
+# obj-m += hellomod-2.o
+# obj-m += chardev-1.o
+
+all:
+ make -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules
+
+clean:
+ make -C /lib/modules/$(shell uname -r)/build M=$(PWD) clean
+cassini/home/peter/bo/2022ss/bs/20220404> ln -sf Makefile-modules-1 Makefile
+cassini/home/peter/bo/2022ss/bs/20220404> echo /lib/modules/$(shell uname -r)/build
+bash: shell: Kommando nicht gefunden.
+/lib/modules//build
+cassini/home/peter/bo/2022ss/bs/20220404> echo /lib/modules/$(uname -r)/build
+/lib/modules/4.19.0-12-amd64/build
+cassini/home/peter/bo/2022ss/bs/20220404> ls /lib/modules/4.19.0-12-amd64/build
+arch include Makefile Module.symvers scripts tools
+cassini/home/peter/bo/2022ss/bs/20220404> uname
+Linux
+cassini/home/peter/bo/2022ss/bs/20220404> uname -r
+4.19.0-12-amd64
+cassini/home/peter/bo/2022ss/bs/20220404> pwd
+/home/peter/bo/2022ss/bs/20220404
diff --git a/20220404/modules-1.txt b/20220404/modules-1.txt
new file mode 100644
index 0000000000000000000000000000000000000000..d0b19f27400f8df15bcb3f7054f98ac8a2407d08
--- /dev/null
+++ b/20220404/modules-1.txt
@@ -0,0 +1,33 @@
+-rw-r--r-- 1 peter peter 270648 Apr 4 14:19 hellomod-1.ko
+cassini/home/peter/bo/2022ss/bs/20220404> ./hellomod-1.ko
+bash: ./hellomod-1.ko: Keine Berechtigung
+cassini/home/peter/bo/2022ss/bs/20220404> chmod +x hellomod-1.ko
+cassini/home/peter/bo/2022ss/bs/20220404> ./hellomod-1.ko
+bash: ./hellomod-1.ko: Kann die Binärdatei nicht ausführen: Fehler im Format der Programmdatei
+cassini/home/peter/bo/2022ss/bs/20220404> chmod -x hellomod-1.ko
+cassini/home/peter/bo/2022ss/bs/20220404> insmod hellomod-1.ko
+bash: insmod: Kommando nicht gefunden.
+cassini/home/peter/bo/2022ss/bs/20220404> sudo insmod hellomod-1.ko
+[sudo] Passwort für peter:
+cassini/home/peter/bo/2022ss/bs/20220404> sudo rmmod hellomod-1.ko
+cassini/home/peter/bo/2022ss/bs/20220404> cat hellomod-1.c
+/*
+ * hello-1.c - The simplest kernel module.
+ */
+#include <linux/module.h> /* Needed by all modules */
+#include <linux/kernel.h> /* Needed for KERN_INFO */
+
+int init_module(void)
+{
+ printk(KERN_INFO "Hello world 1.\n");
+
+ /*
+ * A non 0 return means init_module failed; module can't be loaded.
+ */
+ return 0;
+}
+
+void cleanup_module(void)
+{
+ printk(KERN_INFO "Goodbye world 1.\n");
+}
diff --git a/20220404/modules-2.txt b/20220404/modules-2.txt
new file mode 100644
index 0000000000000000000000000000000000000000..be8dd1125da58e01eb6ab1b40f9045dccd1400cb
--- /dev/null
+++ b/20220404/modules-2.txt
@@ -0,0 +1,8 @@
+cassini/home/peter/bo/2022ss/bs/20220404> sudo dmesg
+[...]
+[1583119.050593] hellomod_1: loading out-of-tree module taints kernel.
+[1583119.050600] hellomod_1: module license 'unspecified' taints kernel.
+[1583119.050601] Disabling lock debugging due to kernel taint
+[1583119.050666] hellomod_1: module verification failed: signature and/or required key missing - tainting kernel
+[1583119.051455] Hello world 1.
+[1583136.476867] Goodbye world 1.
diff --git a/20220404/modules-3.txt b/20220404/modules-3.txt
new file mode 100644
index 0000000000000000000000000000000000000000..2e92a6ca2c886b3b7b920d67ff636c2df6060563
--- /dev/null
+++ b/20220404/modules-3.txt
@@ -0,0 +1,4 @@
+cassini/home/peter/bo/2022ss/bs/20220404> sudo dmesg
+[...]
+[1583551.529893] Hello world 2.
+[1583557.018894] Goodbye world 2.
diff --git a/20220404/modules-4.txt b/20220404/modules-4.txt
new file mode 100644
index 0000000000000000000000000000000000000000..00b0a49562cef65640b80b7eecb3ecb21ce6f01e
--- /dev/null
+++ b/20220404/modules-4.txt
@@ -0,0 +1,6 @@
+[1584035.731938] I was assigned major number 241. To talk to
+[1584035.731939] the driver, create a dev file with
+[1584035.731940] 'mknod /dev/chardev c 241 0'.
+[1584035.731940] Try various minor numbers. Try to cat and echo to
+[1584035.731941] the device file.
+[1584035.731941] Remove the device file and module when done.
diff --git a/20220404/modules-5.txt b/20220404/modules-5.txt
new file mode 100644
index 0000000000000000000000000000000000000000..a82d2ec284069fb1fe7448ca66847a5ddba9ee23
--- /dev/null
+++ b/20220404/modules-5.txt
@@ -0,0 +1,15 @@
+cassini/home/peter/bo/2022ss/bs/20220404> mkdir dev
+cassini/home/peter/bo/2022ss/bs/20220404> mknod dev/chardev c 241 0
+mknod: dev/chardev: Die Operation ist nicht erlaubt
+cassini/home/peter/bo/2022ss/bs/20220404> sudo mknod dev/chardev c 241 0
+cassini/home/peter/bo/2022ss/bs/20220404> ls -l dev/
+insgesamt 0
+crw-r--r-- 1 root root 241, 0 Apr 4 14:39 chardev
+cassini/home/peter/bo/2022ss/bs/20220404> ls -l /dev/tty
+crw-rw-rw- 1 root tty 5, 0 Apr 4 14:22 /dev/tty
+cassini/home/peter/bo/2022ss/bs/20220404> cat dev/chardev
+I already told you 0 times Hello world!
+cassini/home/peter/bo/2022ss/bs/20220404> cat dev/chardev
+I already told you 1 times Hello world!
+cassini/home/peter/bo/2022ss/bs/20220404> cat dev/chardev
+I already told you 2 times Hello world!
diff --git a/20220404/nix-hello.c b/20220404/nix-hello.c
new file mode 100644
index 0000000000000000000000000000000000000000..cc2018703757a875b70c2aa3fd1a104d7e870301
--- /dev/null
+++ b/20220404/nix-hello.c
@@ -0,0 +1,15 @@
+int main (void)
+{
+ char *p = (char *) 0xb8000000;
+ *p++ = 'H';
+ *p++ = 0x04;
+ *p++ = 'e';
+ *p++ = 0x02;
+ *p++ = 'l';
+ *p++ = 0x01;
+ *p++ = 'l';
+ *p++ = 0x06;
+ *p++ = 'o';
+ *p++ = 0x03;
+ return 0;
+}
diff --git a/20220404/os-layers-1.jpg b/20220404/os-layers-1.jpg
new file mode 120000
index 0000000000000000000000000000000000000000..6dc99e9e12dbc84e908c37974c7d528be014d587
--- /dev/null
+++ b/20220404/os-layers-1.jpg
@@ -0,0 +1 @@
+../common/os-layers-1.jpg
\ No newline at end of file
diff --git a/20220404/os-layers-2.jpg b/20220404/os-layers-2.jpg
new file mode 120000
index 0000000000000000000000000000000000000000..4da385ea396af0f9c7ed79b23a183a3b5618b445
--- /dev/null
+++ b/20220404/os-layers-2.jpg
@@ -0,0 +1 @@
+../common/os-layers-2.jpg
\ No newline at end of file
diff --git a/20220404/os-layers-3.jpg b/20220404/os-layers-3.jpg
new file mode 120000
index 0000000000000000000000000000000000000000..eaf5b599709e39d1c51dfdac28843c31b3fa971c
--- /dev/null
+++ b/20220404/os-layers-3.jpg
@@ -0,0 +1 @@
+../common/os-layers-3.jpg
\ No newline at end of file
diff --git a/20220404/os-layers-4.jpg b/20220404/os-layers-4.jpg
new file mode 120000
index 0000000000000000000000000000000000000000..efcbbd1827ff55f225fee0b77b8bfb5c6cff980c
--- /dev/null
+++ b/20220404/os-layers-4.jpg
@@ -0,0 +1 @@
+../common/os-layers-4.jpg
\ No newline at end of file
diff --git a/20220404/os-layers-5.jpg b/20220404/os-layers-5.jpg
new file mode 120000
index 0000000000000000000000000000000000000000..91cabe9241f19ece833cb22e8f16587153f246a2
--- /dev/null
+++ b/20220404/os-layers-5.jpg
@@ -0,0 +1 @@
+../common/os-layers-5.jpg
\ No newline at end of file
diff --git a/20220404/philosophy.c b/20220404/philosophy.c
new file mode 100644
index 0000000000000000000000000000000000000000..e9f508a501d9ec66d02e0636a9f6c71f2c7a8594
--- /dev/null
+++ b/20220404/philosophy.c
@@ -0,0 +1,8 @@
+#include <stdio.h>
+#include "answer.h"
+
+int main (void)
+{
+ printf ("The answer is %d.\n", answer ());
+ return 0;
+}
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