#include <iostream>

using namespace std;

unsigned long long silnia(unsigned n)
{
    if(n == 0 || n == 1)
        return 1;
    return n * silnia(n-1);
}

int main()
{
    for(unsigned i = 0; i <= 20; ++i)
        cout << i << "! = " << silnia(i) << endl;

    return 0;
}