Task A

Calculate a + b

Example:

Input:

2 3

Output:

5

Task B

Reverse a string

Example:

Input:

Python

Output:

nohtyP

Task C

Find a maximum in a sequence

Example:

Input:

1 5 3 9 2

Output:

9

Task D

Calculate a factorial of a number n

f(n) = n * (n - 1) * ... * 1

Example:

Input:

5

Output:

120