import java.util.*;

public class MyArrayStack<E> implements MyStack<E> {

    private ArrayList<E> list = new ArrayList<>();
    
    public void push(E item) {
        list.add(item);
    }
    
    public E peek() {
        return list.get(list.size()-1);
    }
    
    public E pop() {
        return list.remove(list.size()-1);
    }
    
    public boolean empty() {
        return list.size()==0;
    }
    
    public String toString() {
        StringBuilder sb = new StringBuilder();
        sb.append("top\n");
        for(int i=list.size()-1; i>=0; i--)
            sb.append(list.get(i) + "\n");
        sb.append("bottom");
        return sb.toString();
    }
    
    public static void main(String[] args) {
        
        MyArrayStack<Character> stk = new MyArrayStack<>();
        
        for(char ch = 'A'; ch<='Z'; ch++)
            stk.push(ch);
        
        System.out.println(stk);
        
        for(int i=0; i<10; i++)
            stk.pop();
        
        System.out.println(stk.peek());
        
        System.out.println(stk);
        
        while(!stk.empty())
            stk.pop();
        
        System.out.println(stk);
    }
}