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;
signed main(){
  long long a,b=1;
  cin>>a;
  for(int i=1;i<=a;i++){
    b=b*i;
  }
  cout<<b<<"\n";
}

