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, smaller, bigger, i, common, ans;

  scanf("%d%d", &a, &b);
  if(a > b) {
    bigger = a;
    smaller = b;
  } else {
    bigger = b;
    smaller = a;
  }
  for(i = smaller; i > 0; i--) {
    if(smaller % i == 0 && bigger % i == 0) {
      ans = i;
      break;
    }
  }
  printf("%d\n", ans);
  return 0;
}