#include<iostream>
#include<string>
#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
int main(void){
	long long int a=1;
    int n;
    cin>>n;

	for(int i=1;i<=n;i++){
        a*=i;
	}
    cout<<a<<endl;

	return 0;
}