// import java.lang.System;

class A {
    public A() {
        System.out.println("1");
        m1();
    }

    public A(int i) {
        System.out.println("2");
    }

    public A(A a) {
        System.out.println("3");
    }

    public void m1() {
        System.out.println("4");
    }
}

class B extends A{
    A a;

    public B(A a) {
        System.out.println("5");
    }

    public B() {
        this(new A(0));
        System.out.println("6");
    }

    @Override
    public void m1() {
        System.out.println("7");
    }
}

public class Main {
    public static void main(String[] args) {
        A a = new B();
    }
}