public class KStack
{
	private KNode head;
	private int length;
	public KStack()
	{
		length = 0;
	}
	public int[] peek()
	{
		return head.getData();
	}
	public int[] pop()
	{
		int[] output = head.getData();
		head = head.getNext();
		length--;
		return output;
	}
	public void push(int[] i)
	{
		head = new KNode(i,head);
		length++;
	}
	public boolean hasNext()
	{
		return head != null;
	}
	public int getLength()
	{
		return length;
	}
	public String toString()
	{
		String output = "";
		for(KNode tmp = head; tmp != null; tmp=tmp.getNext())
		{
			output += tmp.getData() + " ";
		}
		return output;
	}
	public int[][] toArray()
	{
		int[][] output = new int[length][4];
		int i = length-1;
		for(KNode tmp = head; tmp != null; tmp = tmp.getNext())
		{
			output[i] = tmp.getData();
			i--;
		}
		return output;
	}

}