//Circumscribed Circle of a Triangle

#include<iostream>
using namespace std;

int fac(int n){
    if(n == 0 || n == 1) return 1;
    
    return (n * fac(n -1));
}

int main(void){
    int n, res;
    
    cin >> n;
    
    res = fac(n);
    
    cout << res << endl;
    
    return 0;
}