#include <iostream>

using namespace std;

int Factorial (int f) {
    int i = 1;
    int ans = 1;
    if ( f >= 0) {
    	for (i = 1; i <= f ; i++ ) {
    		ans *= i;
    	}
    	return ans;
    } else {
        return 1;
    }
}

int main () {
    int a;
    cin >> a;
    cout << Factorial(a);
    return 0;
}