// The linked list based implementation for the NumberStack ADT
// Your name here

public class LinkedNumberStack implements NumberStack
{
    // instance variable
    private LNode m_top;

    // check whether the stack is empty
    public boolean isEmpty()
    {       
        if (m_top == null)
            return true;
        else
            return false;
    }

    // check whether the stack is full
    public boolean isFull()
    {
        return false;
    }
    
    // return the element at the top of the stack
    public int top()
    { 
        if (isEmpty())
            throw new RuntimeException("top attempted on an empty stack");
        else
            return m_top.getInfo();
    }

    // push a value onto the stack
    public void push(int v)
    {
        // TODO: implement this method
    }

    // remove and return the value at the top of the stack
    public int pop()
    { 
        // TODO: implement this method
		
        return -1; // replace this statement with your own return
    }

    // return the number of elements on the stack
    public int size()
    {       
        // TODO: implement this method
		
        return -1; // replace this statement with your own return
    }

    // return a string representation of the stack
    @Override    
    public String toString()
    {
        String stackContent = "";
        LNode current = m_top;

        while (current != null)
        {
            stackContent += current.getInfo() + " ";
            current = current.getLink();
        }

        return stackContent;    
    }
}