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 JAVA (judge verdict: Accepted)

import java.util.Scanner;
public class Main{
    public static void main(String[] args){
	int a,b,hz,rem;
	Scanner scan =new Scanner(System.in);
	a=scan.nextInt();
	b=scan.nextInt();
	if(b>a){
	    hz=a;
	    a=b;
	    b=hz;
	}
	rem=a%b;
        while(rem!=0){
	    a=b;
	    b=rem;
	    rem=a%b;
	}
	System.out.println(b);
    }
}