// @BEGIN_OF_SOURCE_CODE

#include <iostream>
#include <cstring>

using namespace std;

int main ()
{
    int n;

    scanf("%d", &n);

    long long fact = 1;

    for ( int i = 1; i <= n; i++ )
        fact *= i;

    cout << fact << endl;

    return 0;
}

// @END_OF_SOURCE_CODE