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: Accepted)

#include <stdio.h>

main(){
  int x,y,i,j;
  
  scanf("%d%d",&x,&y);
  if(x>y){
    j=x%y;
    for(i=j;i>0;i--){
      if(y%i == 0 && j%i == 0){
	printf("%d\n",i);
	break;
      }
    }
  }
  
  if(x<y){
    j=y%x;
    for(i=j;i>0;i--){
      if(x%i == 0 && j%i == 0){
	printf("%d\n",i);
	break;
      }
    }
  }
  
  if(x==y)printf("%d\n",x);  
  
  return 0;
}