diff --git a/.DS_Store b/.DS_Store
new file mode 100644
index 0000000..3d1adcf
Binary files /dev/null and b/.DS_Store differ
diff --git a/lesson_1/.DS_Store b/lesson_1/.DS_Store
new file mode 100644
index 0000000..dbe9b46
Binary files /dev/null and b/lesson_1/.DS_Store differ
diff --git a/lesson_1/task1.py b/lesson_1/task1.py
new file mode 100644
index 0000000..a84684f
--- /dev/null
+++ b/lesson_1/task1.py
@@ -0,0 +1,5 @@
+num_arr = input().split(" ")
+num_sum = 0
+for i in num_arr:
+    num_sum += float(i)
+print(num_sum)
diff --git a/lesson_1/task2.py b/lesson_1/task2.py
new file mode 100644
index 0000000..1e9148c
--- /dev/null
+++ b/lesson_1/task2.py
@@ -0,0 +1,5 @@
+current_str = input()
+while(True):
+    replace_arr = input().split("->")
+    current_str = current_str.replace(replace_arr[0], replace_arr[1])
+    print(current_str)
diff --git a/lesson_1/task3.py b/lesson_1/task3.py
new file mode 100644
index 0000000..b1d6d1b
--- /dev/null
+++ b/lesson_1/task3.py
@@ -0,0 +1,5 @@
+import math
+
+num_arr = input().split(" ")
+for i in num_arr:
+    print(int(math.floor(abs(float(i)))), end=" ")
diff --git a/lesson_1/task4.py b/lesson_1/task4.py
new file mode 100644
index 0000000..65d43aa
--- /dev/null
+++ b/lesson_1/task4.py
@@ -0,0 +1,5 @@
+num_arr = input().split(" ")
+num_sum = 0
+for i in num_arr:
+    num_sum += float(i) ** 2
+print(num_sum)
diff --git a/lesson_1/task5.py b/lesson_1/task5.py
new file mode 100644
index 0000000..0f0b7a5
--- /dev/null
+++ b/lesson_1/task5.py
@@ -0,0 +1,4 @@
+unencoded_str = input().replace(" ", "")
+key = int(input())
+for i in unencoded_str:
+    print(chr(96 + (ord(i) + key - 96) % 26), end="")
diff --git a/lesson_2/dearchiver_lwz.py b/lesson_2/dearchiver_lwz.py
new file mode 100644
index 0000000..8dda575
--- /dev/null
+++ b/lesson_2/dearchiver_lwz.py
@@ -0,0 +1,55 @@
+import math
+import sys
+
+if not (2 <= len(sys.argv) <= 3):
+    print('Usage: python', sys.argv[0], '{encoded_file}.lwz (output_file)')
+    exit(-1)
+
+in_path = sys.argv[1]
+
+out_path = sys.argv[2] if len(sys.argv) == 3 else sys.argv[1][:-4][:sys.argv[1][:-4].find('.')] + '_dec' \
+                                                  + sys.argv[1][:-4][sys.argv[1][:-4].find('.'):]
+
+dictionary = {i: (i,) for i in range(256)}
+
+current_bytes = []
+
+with open(in_path, 'rb') as file_in:
+    with open(out_path, 'wb') as file_out:
+        bites = math.ceil(math.log2(len(dictionary)))
+        bytes = bites // 8
+        if bytes % 8 == 0:
+            bytes += 1
+        sym = int.from_bytes(file_in.read(bytes), byteorder='little')
+        file_out.write(bytearray(dictionary[sym]))
+        current_bytes.append(dictionary[sym][0])
+        current_bytes.append(sym)
+        current_bytes = list(dictionary[sym])
+        while(True):
+            bites = math.ceil(math.log2(len(dictionary)))
+            bytes1 = bites // 8
+            bytes1 += 1
+            sym = file_in.read(bytes1)
+            if not sym:
+                break
+            sym = int.from_bytes(sym, byteorder='little')
+            #print('byte array:', current_bytes)
+            #print('int symbol:', sym)
+            if sym in dictionary:
+                file_out.write(bytearray(dictionary[sym]))
+                current_bytes.append(dictionary[sym][0])
+                dictionary[len(dictionary)] = tuple(current_bytes)
+                current_bytes = list(dictionary[sym])
+            else:
+                current_bytes.append(current_bytes[0])
+                file_out.write(bytearray(current_bytes))
+                dictionary[len(dictionary)] = tuple(current_bytes)
+            #print('=====================')
+
+print('new entries in the dictionary:')
+printable_key = []
+for i in range(256, len(dictionary)):
+    for j in range(len(dictionary[i])):
+        printable_key.append(chr(dictionary[i][j]))
+    print(i, '->', ''.join(printable_key))
+    printable_key.clear()
\ No newline at end of file