new file: tasck12.py
new file: task1.py
new file: task10.py
new file: task13.py
new file: task14.py
new file: task15.py
new file: task16.py
new file: task2.py
new file: task3.py
new file: task4.py
new file: task5.py
new file: task7.py
new file: task8.py
new file: task9.py
