#include<cstdio>
using namespace std;

int ans = {1, 2, 6, 24, 120, 720, 5040, 40320, 362880, 3628800, 39916800, 479001600, 6227020800. 87178291200, 1307674368000, 20922789888000, 355687428096000, 6402373705728000, 121645100408832000, 2432902008176640000};

int main(){
  int a;
  scanf("%d", &a);
  printf("%d\n", ans[a - 1]);
  return 0;
}