что не так?

package com.javarush.task.task08.task0824; import java.util.ArrayList; public class Solution { public static void main(String[] args) { ArrayList<Human> ma = new ArrayList<>(); ArrayList<Human> pa = new ArrayList<>(); ArrayList<Human> child1 = new ArrayList<>(); Human human = new Human("grandma1", false, 65, ma); Human human1 = new Human("grandma2", false, 66, pa); Human human2 = new Human("grandpa1", true, 70, ma); Human human3 = new Human("grandpa2", true, 72, pa); Human human4 = new Human("ma", false, 40, child1); Human human5 = new Human("pa", true, 43, child1); Human human6 = new Human("child1", true, 10); Human human7 = new Human("child2", true, 18); Human human8 = new Human("child3", false, 16); ma.add(human4); pa.add(human5); child1.add(human6); child1.add(human7); child1.add(human8); System.out.println(human); System.out.println(human1); System.out.println(human2); System.out.println(human3); System.out.println(human4); System.out.println(human5); System.out.println(human6); System.out.println(human7); System.out.println(human8); } public static class Human{ String name; boolean sex; int age; ArrayList<Human> children = new ArrayList<>(); public Human(String name, boolean sex, int age, ArrayList<Human> children){ this.name = name; this.sex = sex; this.age = age; this.children = children; } public Human(String name, boolean sex, int age){ this.name = name; this.sex = sex; this.age = age; } public String toString(){ String text = ""; text += "Name: " + this.name; text += ", sex: " + (this.sex ? "men" : "women"); text += ", age: " + this.age; int childCount = this.children.size(); if(childCount > 0) { text += ", children: " + this.children.get(0).name; for (int i = 1; i < childCount; i++) { Human child = this.children.get(i); text += ", " + child.name; } } return text; } } }