using System;

using System.Collections;                   

public class Program

{

    public class MyStack

    {

        private int size = 0;

        private int count= 0;

        private Object[] stack=null;

        public MyStack(int size=10) 

        {   stack= new Object[size];

            this.size= size;

        }

        public Object Push(Object ob)

        {   if(count < size)

            {   return stack[count++]= ob;

            }

            else return null;           

        }

        public Object Pop()

        {   if(count > 0)

            {   return stack[--count];

            }

            else return null;

        }

        public Object Peek()

        {   if(count > 0)

            {   return stack[count-1];

            }

            else return null;

        }

        public int Count

        {   get { return count; }

        }

    }

    public static void Main()

    {

         var emo = new MyStack(20);

        for (int i=1; i<=10; i++)

        {

            emo.Push(i);

            Console.Write("{0,3}",emo.Peek());

        }

        Console.WriteLine(); 

        while(emo.Count>0)

        {

            int a= (int)emo.Pop();

        Console.Write("{0,3}", a);

        }

    }

}