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, d, n;
     scanf("%d %d", &a, &b);
     for(n=1;n<a+1;n++){
          if((a%n==0)&&(b%n==0)){
               d=n;
          }
     }
     printf("%d\n", d);

     return 0;
}