Find the GCD (Greatest Common Divisor) of two numbers

This program considers x and y as input.If both the numbers x and y are 0 then GCD is 0.If either of the two number is 0 then the next non-zero number is GCD.If the fist two conditions are not satisfied then the smaller number is subtracted from the larger numner.This process continous until the number are equivalent to each other.When both the numbers are equivalent then x is GCD of two numbers.

#include < stdio.h >
#include < conio.h > 
void main()
{
    int x,y;
    clrscr();
    printf("\nEnter two numbers :");
    scanf("%d %d",&x,&y);
    if(x==0 && y==0)
    printf("\n No GCD");
    else
    if(x==0 && y!=0)
    printf("GCD is %d",y);
    else
    if(x!=0 && y==0)
    printf("GCD is %d",x);
    else
    {
		 while(x!=y)
		{
			if(x>y)
			x=x-y;
			else
			if(x < y)
			y=y-x;
		}
		printf("\n GCD is %d",x);
    }
}