class SingleNode
{
	private int data;
	private SingleNode next;
	public SingleNode(int initialData)
    {
	    data = initialData;
	    next = null;
    }
    public int getData() { return data;}
    public SingleNode getNext() { return next;}
    public void setData(int newData) {data = newData;}
    public void setNext(SingleNode newLink) {next = newLink;}
}

public class SingleLL
{
	protected SingleNode head;
	protected SingleNode tail;
	protected SingleNode cursor;
	
	public SingleLL(){
		head = null;
		tail = null;
		cursor = null;
	}
	public void addNewHead(int element) {
		SingleNode newNode = new SingleNode(element);
		newNode.setNext(head);
		head = newNode;
		if (tail == null) tail = head;
		cursor = head;
	}
	
	public void Insert(int element) {
		SingleNode newNode = new SingleNode(element);
		if (cursor == null) {head = tail = cursor = newNode;}
		else {
			newNode.setNext(cursor.getNext());
			cursor.setNext(newNode); 
			cursor = newNode;//if we advance the cursor
			if (cursor.getNext() == null) tail = cursor;
		}
	}
	public void Delete() {
		if (cursor != tail){
			cursor.setNext(cursor.getNext().getNext());
			if (cursor.getNext() == null) tail = cursor;
		}
	}
	
	public void removeHead() {
		if (head != null) head = head.getNext();
		if (head == null) tail = null;
		cursor = head;
	}
	
	public boolean advanceCursor() {
		if (cursor != tail) {
			cursor = cursor.getNext();
			return true;
		}
		else
			return false;
	}

	public void resetCursor() {
		cursor = head;
	}
	
	public boolean isEmpty() {
		return (cursor == null);
	}

	public int listLength() {
		SingleNode nodePtr = head; //No Constructor call? Is this wrong?
		int answer = 0;
		while (nodePtr != null) {
			answer++;
			nodePtr = nodePtr.getNext();
		}
		return answer;
	}
	
	public boolean listSearch(int target) {
		SingleNode nodePtr = head;
		while (nodePtr != null) {
			if (target == nodePtr.getData()) {
				cursor = nodePtr;
				return true;
			}
			nodePtr = nodePtr.getNext();
		}
		return false;
	}
	
	public boolean listPosition(int position) throws Exception{
		SingleNode nodePtr = head;
		int i = 1;
		if (position <= 0) throw new Exception("You have asked for position: " + position);//Exception handling
		while (i<position && nodePtr != null){
			nodePtr = nodePtr.getNext();
			i++;
		}
		if (nodePtr != null) cursor = nodePtr;
		return (nodePtr != null);
	}
	
	public static SingleLL listCopy(SingleLL source) {
		SingleLL newList = new SingleLL();
		SingleNode nodePtr = source.head;
		while (nodePtr != null) {
			newList.Insert(nodePtr.getData());
			nodePtr = nodePtr.getNext();
		}
		return newList;
	}
	
	public int getNodeData() throws Exception {
		if (cursor == null) throw new Exception("List is Empty"); 
		return (cursor.getData());
	}
	
	public void setNodeData(int element) throws Exception {
		if (cursor == null) throw new Exception("List is Empty"); 
		cursor.setData(element);
	}
	
	public static void PrintList(SingleLL source) throws Exception{
		source.resetCursor();
		if(source.isEmpty()) System.out.println("Empty List");
		System.out.print("Head: ");
		System.out.print(source.getNodeData()+"");
		while(source.advanceCursor())
		{
			System.out.print("->"+source.getNodeData());
		}
		System.out.println(" :Tail");
	}
	
	public static void main(String args[]) throws Exception{
		SingleLL List1 = new SingleLL();
		for(int i = 0; i<20; i++) {
			List1.Insert(i);
		}
		PrintList(List1);
	}
}