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, num;
  int i;
  int ans;
  
  scanf("%d%d",&x, &y);
  
  if(x >= y){
    x = x % y;
    num = y;
  }
  else{
    y = y % x;
    num = x;
  }
  
  for(i = 1; i <= num; i++){
    if((x % i) == 0 && (y % i) == 0){
      ans = i;
    }
  }
  
  printf("%d\n", ans);
  
  return 0;
}