#include <iostream>
using namespace std;
int main(){
	int n,i,s=1;
	cin>>n;
	i=1;
	while(i<=n){
		s=s*i;
		i=i+1; 
	}
	cout<<s; 
}
/**************************************************************
	Problem: 1004
	User: fandaohan
	Language: C++
	Result: Accepted
	Time:10 ms
	Memory:2072 kb
****************************************************************/