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,gcd=1,min,flag=0;
  scanf("%d%d",&x,&y);

  i = 2;
  if(x >= y){
    min = y;
    if(x%y == 0){
      gcd = y;
      flag =1;
    }
  }
  else{
    min=x;
    if(y%x == 0){
      gcd = x;
      flag =1;
    }
  }

  while(min/2 >= i && flag ==0){
    if(x%i == 0 && y%i == 0)
      gcd = i;
    i++;
  }
  printf("%d\n",gcd);
  return 0;
}