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(){

  int x,y,i,d;

  scanf("%d %d", &x,&y);

  if(x<y) d=x;
  else d=y;

  for(i=d ; i>0 ; i--){
    if(x%i==0 &&y%i==0)break;
  }

  printf("%d\n", i);

  return 0;
}