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 a, b, i, x, y;    
 
  scanf("%d %d", &a, &b);
 
  for( i = a; i > 0; i--) {
    x = a % i;
    y = b % i;
    if (x == 0 && y == 0) {
     break;
    }
  }

  printf ("%d\n", i);
 
  return 0;
}