Write a program which reads an integer n and prints the factorial of n. You can assume that n ≤ 20.



Input

An integer n (1 ≤ n ≤ 20) in a line.

Output

Print the factorial of n in a line.

Example

Input

5


Output

120
# coding: utf-8
# coding: Shift_JIS
# coding: EUC-JP
# coding: cp932
import math

n = int(input())
print(math.factorial(n))



