Спој листи наизменично

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.NoSuchElementException;
import java.util.Iterator;

class SLLNode<E> {
    protected E element;
    protected SLLNode<E> successor;

    public SLLNode(E element, SLLNode<E> successor) {
        this.element = element;
        this.successor = successor;
    }
}

class SLL<E> {
    private SLLNode<E> first;

    public SLL() {
        first = null;
    }

    public SLLNode<E> getFirst() {
        return first;
    }

    public void insertFirst(E o) {
        SLLNode<E> insert = new SLLNode<E>(o, first);
        first = insert;
    }

    public void insertLast(E o) {
        if(first != null) {
            SLLNode<E> tmp = first;
            while(tmp.successor != null)
                tmp = tmp.successor;
            SLLNode<E> insert = new SLLNode<E>(o, null);
            tmp.successor = insert;
        } else insertFirst(o);
    }

    public Iterator<E> iterator() {
        return new LRIterator();
    }

    private class LRIterator<E> implements Iterator<E> {
        private SLLNode<E> place, current;

        private LRIterator() {
            place = (SLLNode<E>)first;
            current = null;
        }

        public boolean hasNext() {
            return place != null;
        }

        public E next() {
            if(place == null)
                throw new NoSuchElementException();
            E nextElement = place.element;
            current = place;
            place = place.successor;
            return nextElement;
        }
    }
}

public class SpecialSLLJoin {

    public static SLL<Integer> specialJoin(SLL<Integer> listOne, SLL<Integer> listTwo) {
        SLLNode<Integer> listOneNode = listOne.getFirst(), listTwoNode = listTwo.getFirst();
        SLL<Integer> specialOne = new SLL<Integer>();
        while(listOneNode != null&&listTwoNode != null) {
            specialOne.insertLast(listOneNode.element);
            if(listOneNode.successor != null) {
                listOneNode = listOneNode.successor;
                specialOne.insertLast(listOneNode.element);
            }
            listOneNode = listOneNode.successor;

            specialOne.insertLast(listTwoNode.element);
            if(listTwoNode.successor != null) {
                listTwoNode = listTwoNode.successor;
                specialOne.insertLast(listTwoNode.element);
            }
            listTwoNode = listTwoNode.successor;
        }

        if(listOneNode != null) {
            while(listOneNode != null) {
                specialOne.insertLast(listOneNode.element);
                listOneNode = listOneNode.successor;
            }
        }

        if(listTwoNode != null) {
            while(listTwoNode != null) {
                specialOne.insertLast(listTwoNode.element);
                listTwoNode = listTwoNode.successor;
            }
        }

        return specialOne;
    }

    public static void main(String[] args) throws IOException{

        SLL<Integer> lista1 = new SLL<Integer>();
        SLL<Integer> lista2 = new SLL<Integer>();

        BufferedReader stdin = new BufferedReader(new InputStreamReader(
                System.in));
        String s = stdin.readLine();
        int N = Integer.parseInt(s);
        s = stdin.readLine();
        String[] pomniza = s.split(" ");
        for (int i = 0; i < N; i++) {
            lista1.insertLast(Integer.parseInt(pomniza[i]));
        }

        s = stdin.readLine();
        N = Integer.parseInt(s);
        s = stdin.readLine();
        pomniza = s.split(" ");
        for (int i = 0; i < N; i++) {
            lista2.insertLast(Integer.parseInt(pomniza[i]));
        }

        SLL<Integer> spoeni = specialJoin(lista1,lista2);

        Iterator<Integer> it = spoeni.iterator();
        while(it.hasNext()) {
            System.out.print(it.next());
            if(it.hasNext())
                System.out.print(" ");
        }
    }
}