TO FIND WHETHER THE NUMBER IS FIBONACCI OR NOT

#include<stdio.h>
#include<conio.h>
void main()
{
int num,s=0,x=-1,y=1,flag=0;
clrscr();
printf("Enter The Number:");
scanf("%d",&num);
while (s<num)
    {
    s=x+y;
    if (s==num)
    {
    printf("%d belongs to fibonacci series",num);
    flag=1;
    break;
    }
x=y;
y=s;
}
if (flag==0)
   printf("%d is not in fibonacci series",num);
   getch();
   }