package javaapplication8;
import java.util.*;

public class JavaApplication8 {
	public JavaApplication8() {
	}

	public static void main(String args[])  {
		System.out.println("Starting App");
		PFStack st = new PFStack();
                st.push(new Integer(10));
                st.push(new Integer(20));
                st.push(new Integer(30));

                System.out.println("Top of stack is " + (Integer)st.peek());
                try {
                    st.pop();
                    System.out.println("pop 1");
                    st.pop();
                    System.out.println("pop 2");
                    st.pop();
                    System.out.println("pop 3");
                    st.pop(); // This line causes an exception and throws the exception
                    System.out.println("pop 4");
                    st.pop();
                } catch(EmptyPFStackException e) {
                    e.printStackTrace();
                    System.out.println("successfully caught exception and finished executing");
                }

	}
}

class PFStack {
    private Vector m_theData;

    public PFStack() {
        m_theData = new Vector();
    }
    public void push (Object item) {
        m_theData.addElement(item);
    }
    public Object peek() {
        return m_theData.lastElement();
    }
    public Object pop() throws EmptyPFStackException {
        try {
            Object result = m_theData.lastElement();
            m_theData.removeElementAt(m_theData.size()-1);
            return result;
        } catch(Exception e) {
            throw new EmptyPFStackException("Reached end of stack");
        }

    }
}

class EmptyPFStackException extends Exception {
    public EmptyPFStackException() {
    }

    public EmptyPFStackException(String msg) {
        super(msg);
    }
}