#include <stdio.h>
#include <conio.h>
#include <stdlib.h>


int main()
{
  int n,i;
  int res;

  unsigned long long fact = 1;
  printf("Enter number: ");
  scanf("%d",&n);

  if(n >= -7 && n <= 7)
  {
    if(n <= 0)
    {
      printf("Error");
    }

    else
    {
      for(i = 1; i <= n; i++)
      {
        fact *= i;
      }
    }

    printf("%llu\n", fact);
  }

  else
  {
    printf("Error");
  }
  _getch();
  return 0;
}