#include <bits/stdc++.h>
using namespace std;
int main(){
  int n,s=1;
  cin>>n;
  for(int i=1;i<=n;i++){
  	s=s*i;
  }
  cout<<s;
    return 0;
}
/**************************************************************
	Problem: 1004
	User: wangyousi
	Language: C++
	Result: Accepted
	Time:10 ms
	Memory:2072 kb
****************************************************************/