#include <bits/stdc++.h>
using namespace std;
int main()
{
int n,s=0;
cin>>n;
for(int i=1;i<=n;i++){
	s*=i;
} 

cout<<s<<endl;
return 0;

}

/**************************************************************
	Problem: 1004
	User: mc002
	Language: C++
	Result: Wrong Answer
****************************************************************/