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
from functools import reduce
print(reduce(lambda x, y: x*y, [x for x in range(1, int(input())+1)]))