#include 

using namespace std;

int factorial(int x) {
    if(x == 1) {
        return 1;
    }
    return factorial(x - 1) * x;
}
int main()
{
    int n;
    cin >> n;
    cout << factorial(n) << endl;
    return 0;
}

//factorial(5) = 120
// factorial(4) * 5 = 24 * 5 = 120
//factorial(3) * 4 = 6  * 4 = 24
// factorial(2) * 3 = 2 * 3 = 6
//factorial(1) * 2 = 1 * 2 = 2
// factorial(1) = 1