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<cstdio>
#include<iostream>

using namespace std;

int main(){
    long long k=1;
    for(int i=1;i<=20;i++){
        k*=i;
    }
    cout<<k<<endl;
        return 0;
}