#include<bits/stdc++.h>
using namespace std;
int n,sum=1;
int main(){
    cin>>n;
    int i=1;
    while(i<=n){
        sum*=i;
        i++;
    }
    cout<<sum;
    return 0;
}
/**************************************************************
	Problem: 1004
	User: wuweimo
	Language: C++
	Result: Accepted
	Time:9 ms
	Memory:2072 kb
****************************************************************/