#include <iostream>
#include <string>

using namespace std;

string ns[]={"1","1","2","6","24","120","720","5040","40320","362880","3628800","39916800","479001600","6227020800","87178291200","1307674368000","20922789888000","355687428096000","6402373705728000","121645100408832000","2432902008176640000"};

int main(){
  int n;
  cin >> n;
  cout << ns[n] << endl;
}