#include <iostream>
using namespace std;

long long factorial(int n);

int main() {

    int n;
    cin >> n;

    cout << factorial(n) << endl;

    return 0;
}

long long factorial(int n) {

    long long t=1;
    int i;
    // write your code here......
    for(i=2;i<=n;i++)
    {
        t*=i;
    }
    return t;
}