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
#include<iostream>
using namespace std;

int main() {
	int n;
	long long d=1;
	cin >> n;
	for (int i = 0; i < n; i++){
		d *= (i + 1);
	}
	cout << d << endl;
	
}