Cannot compile it

package com.codegym.task.task08.task0824; /* Make a family */ import java.util.*; public class Solution { ArrayList<Human> childs = new ArrayList<>(); ArrayList<Human> olderChilds1 = new ArrayList<>(); ArrayList<Human> olderChilds2 = new ArrayList<>(); ArrayList<Human> nochilds = new ArrayList<>(); Human grandfather1 = new Human("Aleksandr", true, 57, olderChilds1); Human grandfather2 = new Human("Maxim", true, 54, olderChilds2); Human grandmother1 = new Human("Marina", false, 58, olderChilds1); Human grandmother2 = new Human("Kasandra", false, 54, olderChilds2); Human father = new Human("Morin", true, 30, childs); olderChilds1.add(father); Human mother = new Human("Drixy", false, 28, childs); olderChilds2.add(mother); Human child1 = new Human("Edward", true, 6, nochilds); childs.add(child1); Human child2 = new Human("Nancy", false, 4, nochilds); childs.add(child2); Human child3 = new Human("Max", true, 2, nochilds); childs.add(child3); System.out.println(grandfather1); System.out.println(grandfather2); System.out.println(grandmother1); System.out.println(grandmother2); System.out.println(father); System.out.println(mother); System.out.println(child1); System.out.println(child2); System.out.println(child3); } // two grandfathers, two grandmothers, one father, one mother, and three children. public static class Human { String name; boolean sex; int age; ArrayList<Human> children; public Human(String name, boolean sex, int age, ArrayList<Human> children){ this.name = name; this.sex = sex; this.age = age; this.children = children; } public String toString() { String text = ""; text += "Name: " + this.name; text += ", sex: " + (this.sex ? "male" : "female"); 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; } } }