text: #include <iostream>
  using std::cout;
  using std::cin;
  using std::endl;
  void fact()
  {
      int val;
      cin >> val;
      int ret = 1;
      while(val > 1)
          ret *= val--;
      cout << ret << endl;
  }
  int main()
  {
      fact();
      return 0;
  }
  