Problem:
Greatest Common Divisor

Write a program which finds the greatest common divisor of two natural numbers a and b

Input

a and b are given in a line sparated by a single space.

Output

Output the greatest common divisor of a and b.

Constrants

1 ≤ a, b ≤ 109

Hint

You can use the following observation:

For integers x and y, if x ≥ y, then gcd(x, y) = gcd(y, x%y)

Sample Input 1

54 20

Sample Output 1

2

Sample Input 2

147 105

Sample Output 2

21

Solution in C (judge verdict: Time Limit Exceeded)

#include<stdio.h>


main()
{

  int x,y,d;

  scanf("%d%d",&x,&y);
  while(1)
  {
      
      if(x>y)
	{
	 
	  x -= y;
	  
	  

	}
      
      if(x>1 && y>1 )
	{
	  
	  d = x;
	  x = y; // ????????§y???x?????£??\??????
	  y = d;
	  if(y%x==0){printf("%d\n",x);break;}  
	
	  //?????????????????¨??§??????if?????????????°??????????????????¨?????§??????
	  	}
      
      
  }
  
     
	  
  return 0;
}