import java.util.EmptyStackException;

public class ArrayStack implements Stack {
	//Data
	protected Object[] items;
	protected int top; 
	
	//Constructors
	public ArrayStack() { this(10); }
	
	public ArrayStack(int n) {
		items = new Object[n];
		top = -1;
	}
	
	public ArrayStack(Object[] data) {
		this(data.length + 10);
		for(int i = 0; i < data.length; i++) push(data[i]);
	}
	
	//Stack methods implementation
	public boolean isEmpty() { return top == -1; }
	   	
	public void push(Object x) throws FullStackException {
		if(isFull()) throw new FullStackException("Stack is full!");
        items[++top] = x;
	}
	
	public Object pop() throws EmptyStackException {
		Object result = top();
		top--;
		return result;
	}
	
	public Object top() throws EmptyStackException {
		if(isEmpty()) throw new EmptyStackException();
		return items[top];
	}

	//Other methods
	public boolean isFull() { return top == items.length - 1; }
	public int capacity() { return items.length; }
}