#include <iostream>
#include <string>

using namespace std;

int main(){
int n;
string fac[21] = {"1","1","2","6","24","120","720","5040","40320","362880","3628800","39916800","479001600","6227020800","87178291200","1307674368000"
			,"20922789888000","355687428096000","6402373705728000","121645100408832000","2432902008176640000"};

cin >> n;
cout << fac[n] << endl;

return 0;
}