#include <fstream>
using namespace std;
ifstream f("fact.in");
ofstream g("fact.out");
int n,p;
int factorial(int n)
{
    if(n==0)return 1;
    else
        return n*factorial(n-1);
}
int main()
{
    f>>n;
    p=factorial(n);
    g<<p;
    return 0;
}