PA07-5

import java.util.*;

public class Main {

    public static int modulusRec(int x, int y) {
        if (x == 0) return 0;
        if (x < y) return x;
        return modulusRec(x - y, y);
    }

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int x = sc.nextInt();
        int y = sc.nextInt();
        if (y < 0) {
            System.out.println("Errrrrrror!!!!!!");
            return;
        }
        System.out.println(modulusRec(5, 3));
    }
}