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;
  cin>>n;
long long ans=1;
  for(int i=1;i<=n;i++) 
    ans*=i;
  cout<<ans<<endl;
  return 0;
}

