class CharStack
{
	class CharNode
	{
		char data;
		CharNode next;

		public CharNode(){data = '\0'; next=null;}
	}

	private CharNode head;


	public CharStack()
	{
		head = null;
	}

	public char top()
	{	//this segment of code done by bobby davenport	
		if(head==null)
			return '\0';
		return head.data;
	}

	public char pop()
	{
		char a = '\0'; 
		if(head!=null) 
		a = head.data;
		head = head.next;
		return a;
	}

	public void push( char c )
	{
	}

	public boolean isEmpty()
	{
	}
}