GreatestCommonDivisor

import java.util.Scanner;

/**
 * Created by Jo on 2/21/2017.
 */
public class GreatestCommonDivisor {
    public static void main(String[] args) {
        Scanner console = new Scanner(System.in);
        int number1 = Integer.parseInt(console.nextLine());
        int number2 = Integer.parseInt(console.nextLine());
        int tempNumber = 0;

        if (number1 == 0) {
            System.out.println(number2);
        } else {
            if (number2 == 0) {
                System.out.println(number1);
            } else {
                if (number1 == number2) {
                    System.out.println(number1);
                } else {
                    if (number1 > number2) {
                        while (number2!= 0) {
                            tempNumber = number2;
                            number2 = number1 % number2;
                            number1 = tempNumber;
                        }
                        System.out.println(number1);
                    } else {
                        while (number1!= 0) {
                            tempNumber = number1;
                            number1 = number2 % number1;
                            number2 = tempNumber;
                        }
                        System.out.println(number2);
                    }
                }
            }
        }
    }
}