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, X, Y;

   scanf("%d %d", &x, &y);

   if(x > y){
      for(i=y; i>=1; i--){
         if(y%i == 0){
            X = x%y;
            if(X%i == 0){
               printf("%d\n", i);
               return 0;
            }
         }
      }
   }

   else if(x < y){
      for(i=x; i>=1; i--){
         if(x%i == 0){
            Y = y%x;
            if(Y%i == 0){
               printf("%d\n", i);
               return 0;
            }
         }
      }
   }

   else
      printf("%d\n", x);
      return 0;

}