diff --git a/lesson_1/task1.py b/lesson_1/task1.py
new file mode 100644
index 0000000..83a08dc
--- /dev/null
+++ b/lesson_1/task1.py
@@ -0,0 +1,15 @@
+# Task №1
+
+def sum(nums):
+    sum = 0
+    for i in nums:
+        sum = sum + i
+    return sum
+
+if __name__ == '__main__':
+    numbers = []
+    n = input()
+    for i in range(int(n)):
+        x = int(input())
+        numbers.append(x)
+    print(sum(numbers))
diff --git a/lesson_1/task2.py b/lesson_1/task2.py
new file mode 100644
index 0000000..f5182f6
--- /dev/null
+++ b/lesson_1/task2.py
@@ -0,0 +1,18 @@
+# Task №2
+
+def str_change(str, old_s, new_s):
+    new_str_list = ''
+    for i in str:
+        if i == old_s:
+            i = new_s
+            new_str_list = new_str_list + i
+        else:
+            new_str_list += i
+    return new_str_list
+
+if __name__ == '__main__':
+    str = input('The string:')
+    old_s = input('Enter the symbol that you want to change:')
+    new_s = input(f'{old_s} -> ')
+    list_string = str
+    print(str_change(list_string, old_s, new_s))
diff --git a/lesson_1/task3.py b/lesson_1/task3.py
new file mode 100644
index 0000000..864df3f
--- /dev/null
+++ b/lesson_1/task3.py
@@ -0,0 +1,11 @@
+# Task №3
+import math
+
+if __name__ == '__main__':
+    input_list = input().split()
+    fabs_int_elements = list()
+    for i in input_list:
+        fabs_elem = math.fabs(float(i))
+        fabs_int_elements.append(int(fabs_elem))
+    print(fabs_int_elements)
+
diff --git a/lesson_1/task4.py b/lesson_1/task4.py
new file mode 100644
index 0000000..d5ca22a
--- /dev/null
+++ b/lesson_1/task4.py
@@ -0,0 +1,22 @@
+# Task №4
+
+def square_num(num_str):
+    num = float(num_str)
+    return num*num
+
+def square_list(list_):
+    new_list = list()
+    for i in list_:
+        new_list.append(square_num(i))
+    return new_list
+
+def sum(list):
+    sum = 0
+    s_list = square_list(list)
+    for i in s_list:
+        sum = sum + i
+    return sum
+
+if __name__ == '__main__':
+    input_list = input().split()
+    print(sum(input_list))
diff --git a/lesson_1/task5.py b/lesson_1/task5.py
new file mode 100644
index 0000000..b764a48
--- /dev/null
+++ b/lesson_1/task5.py
@@ -0,0 +1,23 @@
+# Task №4
+
+def encrypting(message, key):
+    alfabeth = 'ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz'
+    encrypted_message = ''
+    for i in message:
+        index = alfabeth.find(i)
+        new_index = index + key
+        if i in alfabeth:
+            encrypted_message += alfabeth[new_index]
+        else:
+            encrypted_message += i
+    return encrypted_message
+
+
+
+if __name__ == '__main__':
+    message = input('Input the string: ')
+    key = int(input('Input the key: '))
+    print(encrypting(message,key))
+
+#puhtuhavtpj
+