uicfghYKAUScrtvukisb

#include<iostream>
using namespace std;
int main(){
    int a=0,b=1;
    cin >> a;
    if (a==0||a==1){
        cout << "1";
    }
    else{
     	for (int i=1;i <= a;i++){
            b*=i;
        }
        cout << b;
    }   
    return 0;
}