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;
class Main {
	public static void main(String[] args){
		final int Number=100;
		try(Scanner sc = new Scanner(System.in)){
			int N = Integer.parseInt(sc.next());
			int M = Integer.parseInt(sc.next());
			int c =gcd(N,M);
			System.out.println(c);
		}
	}
	public static int gcd(int N, int M){
		int max=Math.max(N, M);
		int min=Math.min(N, M);
		
		if(max%min==0){
			return min;
		}else{
			return gcd(max%min,min);
		}
	}
}