#include <iostream>
#include <fstream>

using namespace std;

ifstream a("fact.in");
ofstream b("fact.out");

int factorial(int x)
{   int i,z;
    i=1;
    z=1;
    if(x!=0)
        while(i<=x)
            {z=z*i;
             i++;
            }
    return z;

}


int main()
{
    int x;
    a>>x;
    b<<factorial(x);

    return 0;
}