NULL

import java.util.ArrayList;
import java.util.*;
//import java.lang.StackOverflowError;
//======================================================================================================================
public class ThirdEleventh {
    public static class MyTreeNode<T>{
        private T data = null;
        private List<MyTreeNode> children = new ArrayList<>();
        private MyTreeNode parent = null;
//-------------------------------------------------------------
        public MyTreeNode(T data) {
            this.data = data; }

        public void addChild(MyTreeNode child) {
            child.setParent(this);
            this.children.add(child); }

       //public void addChild(T data) {
       //    MyTreeNode<T> newChild = new MyTreeNode<>(data);
       //    newChild.setParent(this);
       //    children.add(newChild); }

        public void addChildren(List<MyTreeNode> children) {
            for(MyTreeNode t : children) {
                t.setParent(this);
            }
            this.children.addAll(children);
        }

        public T getData() {
            return data; }

        public List<MyTreeNode> getChildren() {
            return children; }

        //public void setData(T data) {
        //    this.data = data;
        //}

        private void setParent(MyTreeNode parent) {
            this.parent = parent; }

        public MyTreeNode getParent() {
            return parent; }
    }
//======================================================================================================================
    public static void main(String[] args){
        MyTreeNode<String> root = new MyTreeNode<>("Me");
//-------------------------------------------------------------

        MyTreeNode<String> father = new MyTreeNode<>("Father");

        MyTreeNode<String> mother = new MyTreeNode<>("Mother");

        MyTreeNode<String> fGF = new MyTreeNode<>("GrandFather");
        fGF.addChildren(Arrays.asList(
                new MyTreeNode<>("GrandFather's Mother"),
                new MyTreeNode<>("GrandFather's Father")
        ));

        MyTreeNode<String> fGM = new MyTreeNode<>("GrandMother");
        fGM.addChildren(Arrays.asList(
                new MyTreeNode<>("GrandMother's Father"),
                new MyTreeNode<>("GrandMother's Mother")
        ));

        MyTreeNode<String> mGM = new MyTreeNode<>("GrandMother");
        mGM.addChildren(Arrays.asList(
                new MyTreeNode<>("GrandMother's Mother"),
                new MyTreeNode<>("GrandMother's Father")
        ));

        MyTreeNode<String> mGF = new MyTreeNode<>("GrandFather");
        mGF.addChildren(Arrays.asList(
                new MyTreeNode<>("GrandFather's Mother"),
                new MyTreeNode<>("GrandFather's Father")
        ));

        root.addChild(mother);
        root.addChild(father);
        mother.addChild(mGM);
        mother.addChild(mGF);
        father.addChild(fGM);
        father.addChild(fGF);

//-------------------------------------------------------------
        for(MyTreeNode node : root.getChildren()) {
            System.out.print("Child: ");
            System.out.print(node.getParent().getData());
            System.out.print("        Parent: ");
            System.out.println(node.getData());
        }

        for(MyTreeNode node : father.getChildren()) {
            System.out.print("Child: ");
            System.out.print(node.getParent().getData());
            System.out.print("        Parent: ");
            System.out.println(node.getData());
        }

        for(MyTreeNode node : mother.getChildren()) {
            System.out.print("Child: ");
            System.out.print(node.getParent().getData());
            System.out.print("        Parent: ");
            System.out.println(node.getData());
        }

        for(MyTreeNode node : mGF.getChildren()) {
            System.out.print("Child: ");
            System.out.print(node.getParent().getData());
            System.out.print("        Parent: ");
            System.out.println(node.getData());
        }

        for(MyTreeNode node : mGM.getChildren()) {
            System.out.print("Child: ");
            System.out.print(node.getParent().getData());
            System.out.print("        Parent: ");
            System.out.println(node.getData());
        }

        for(MyTreeNode node : fGM.getChildren()) {
            System.out.print("Child: ");
            System.out.print(node.getParent().getData());
            System.out.print("        Parent: ");
            System.out.println(node.getData());
        }

        for(MyTreeNode node : fGM.getChildren()) {
            System.out.print("Child: ");
            System.out.print(node.getParent().getData());
            System.out.print("        Parent: ");
            System.out.println(node.getData());
        }

    }
}
//======================================================================================================================