Problem Statement

A function ~f(x)~ defined for non-negative integer ~x~ satisfies the following conditions:

• ~f(0) = 1~ ;
• ~f(k) = k \times f(k-1)~ for all positive integers ~k~ .

Find ~f(N)~ .

Constraints

• ~N~ is an integer such that ~0 \le N \le 10~ .

Input

The input is given from Standard Input in the following format:

~N~

Output

Print the answer as an integer.

Sample Input 1

2

Sample Output 1

2

We have ~f(2) = 2 \times f(1) = 2 \times 1 \times f(0) = 2 \times 1 \times 1 = 2~ .

Sample Input 2

3

Sample Output 2

6

We have ~f(3) = 3 \times f(2) = 3 \times 2 = 6~ .

Sample Input 3

0

Sample Output 3

1

Sample Input 4

10

Sample Output 4

3628800