#include <stdio.h>

int main()
{
  int i, n, fact = 1;

  printf("Enter a number: ");
  if (scanf("%d", &n) != 1) {
    printf("ERROR: failed to rean a number!\n");
    return -1;
  }
  for (i = 1; i <= n; i++)
    fact *= i;
  printf("Factorial of is %d\n", fact);
  return 0;
}