Program to calculate Factorial Number

 #include<stdio.h>
 #include<conio.h>
  int main()
{ int n, count;
unsigned long long int factorial=1;
printf("Enter an integer: ");
scanf("%d",&n); if ( n< 0)
printf("Error!!! Factorial of negative number doesn't exist.");
 else
 { for(count=1;count<=n;++count)
 { factorial*=count;}
 printf("Factorial = %lu",factorial); }
getch();
}