Simple Factorial

Source: beecrowd

Version: Phuoc Hung OJ Extended

Problem Statement

Compute factorial. PHOJ Extended explicitly includes n=0 and 0!=1.

Input

One integer 0<=n<=12 (PHOJ Extended includes zero).

Output

One integer n!.

Subtasks

• Subtask 1 (20%): 0<=n<=4.
• Subtask 2 (30%): 0<=n<=8.
• Subtask 3 (50%): 0<=n<=12.

Examples

Example 1

Input

4

Output

24

Explanation

123*4=24.

Example 2

Input

0

Output

1

Explanation

The empty product equals 1.