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package com.javarush.task.task20.task2028; import java.util.List; public class Solution { public static void main(String[] args) { List list = new CustomTree(); for (int i = 1; i < 16; i++) { list.add(String.valueOf(i)); } System.out.println("The list size is " + list.size()); System.out.println("The expected parent is 3. The actual parent is " + ((CustomTree) list).getParent("8")); System.out.println("The expected parent is null. The actual parent is " + ((CustomTree) list).getParent("20")); list.remove("3"); System.out.println("The expected parent is null. The actual parent is " + ((CustomTree) list).getParent("8")); list.add("16"); System.out.println("The expected parent is 9. The actual parent is " + ((CustomTree) list).getParent("16")); list.remove("4"); list.remove("5"); list.remove("6"); System.out.println("Expected: true. Actual: " + list.add("20")); System.out.println("The expected parent is 1. The actual parent is " + ((CustomTree) list).getParent("20")); } }