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>
int main(void){
  int x;
  int y;
  int i;

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

return 0;
}