public class StringStack {
 //TODO
	public Node myFront;
	private int mySize;
	
	public class Node{
		Node myNext;
		String myData;
		
		public Node(String data, Node next){
			myNext = next;
			myData = data;
		}	
	}
	
	public StringStack(){
		myFront = null;
		mySize = 0;
	}
	
	public void push(String data){
		Node newFront = new Node(data, myFront);
		myFront = newFront;
		mySize++;
	}
	
	public String pop(){
		String data = myFront.myData;
		myFront = myFront.myNext;
		mySize--;
		return data;
	}
	
	public boolean isEmpty(){
		return (mySize == 0);
	}
}