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,y,gcd = 0,i,small;
  scanf("%d",&x); scanf("%d",&y);
  if(x < y)small = x;
  else small = y;

  for(i = 1; i <= small; i++){
    if(x % i == 0 && y % i == 0)gcd = i;
  }
  printf("%d\n",gcd);
  return 0;
}