import java.util.*;

/*
* ListBuilder main class
*/
public class ListBuilder {

// Fields to keep track of ListComponent object
ListComponent component;
int componentIndex;
// Fields to keep track of ListComposite object
ListComposite composite;
int compositeIndex;
// Level for hierarchy parsing
int level = 0;

// Method which processes an open bracket
public void buildOpenBracket() {
level++;
// Lowest level open bracket
if (level == 1) {
   component = new ListComponent();
   componentIndex = 0;
// Nested open bracket
} else {
   composite = new ListComposite();
   compositeIndex = 0;
}
}

// Method which processes an close bracket
public void buildCloseBracket() {
level--;
// Nested close bracket, add ListComposite to ListComponent
if (level == 1) {
   component.addChild(componentIndex++, composite);
}
}

// Method which processes an integer element
public void buildElement(int element) {
// Lowest level, add to ListComponent
if (level == 1) {
   component.addChild(componentIndex++, new Item(element));
// Nested level, add to ListComposite
} else if (level == 2) {
   composite.addChild(compositeIndex++, new Item(element));
}
}

// Get ListComponent of ListBuilder
public ListComponent getList() {
return component;
}

// Main method which runs upon execution
public static void main(String[] args) {
Scanner s = new Scanner(System.in);
// Initially, query user for input list
String input = s.nextLine().replaceAll("\\s","");
ListBuilder builder = new ListBuilder();
// Apply ListBuilder methods to input
for (char token: input.toCharArray()) {
   if (token == '[') {
   builder.buildOpenBracket();
   } else if (token == ']') {
   builder.buildCloseBracket

Question#1 Suppose that a list can contain items and other lists....