#include <iostream>
using namespace std;

unsigned int kaijo(int n) {
  unsigned int ans = 1;
  for(int i = n; i > 0; i--) {
    ans *= i;
  }
  return ans;
}

int main(void) {
  int n;
  cin >> n;
  cout << kaijo(n) << endl;
  
  return 0;
}