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<bits/stdc++.h>
using namespace std;

int main(){
    int n;
    long long ans=1;

    cin>>n;
    for(int i=1;i<=n;i++)ans*=i;
    cout<<ans<<endl;

    return 0;
}