import java.util.Collection;
import java.util.Deque;
import java.util.Iterator;

/**
* This class consists of two classes - the MyStack and its
* private inner class Node. MyStack implements Deque.
* @param <E>
*/
public class MyStack<E> implements Deque<E> {

/**
* Node class contains
* the value and reference
* to next node.
* @param <E>
*/
private class Node <E> {
   private E value;
   private Node<E> next;

   public Node(E value, Node<E> next) {
         this.value = value;
         this.next = next;
   }
}

/**
* The node representing the
* top of the stack.
*/
private Node<E> top;

/**
* This method checks if
* stack is empty of not.
* @return
*/
@Override
public boolean isEmpty() {
   return top == null;
}

/**
* This method pushes
* the value e on the stack.
* @param e
*/
@Override
public void push(E e) {
   if(top == null) {
         top = new Node(e, null);
   } else {
         Node<E> node = new Node(e, top);
         top = node;
   }
}

/**
* This method pops
* the top node from the stack
* and returns its value if stack isn't empty,
* otherwise returns null.
* @return the value stored at the top of the stack.
*/
@Override
public E pop() {
   if (!isEmpty()) {
         Node<E> tmp = top;
         top = top.next;
         return tmp.value;
   }
   return null;
}

/**
* It returns the value stored
* at the node at the top of
* the stack, returns null if stack is empty.
* @return
*/
@Override
public E peek() {
   if (!isEmpty()) {
         return top.value;
   }
   return null;
}

@Override
public String toString() {
   return super.toString();
}

@Override
public void addFirst(E e) {

}

@Override
public void addLast(E e) {

}

@Override
public boolean offerFirst(E e) {
   return false;
}

@Override
public boolean offerLast(E e) {
   return false;
}

@Override
public E removeFirst() {
   return null;
}

@Override
public E removeLast() {
   return null;
}

@Override
public E pollFirst() {
   return null

Point Class Write a definition of a class named Point that might b...