using System;
using System.Linq;

namespace _03.Stack
{
    public class StartUp
    {
        static void Main(string[] args)
        {
            var stack = new Stack<int>();

            string commandInput = Console.ReadLine();

            while (commandInput != "END")
            {
                var tokens = commandInput
                    .Split(new string[] { " ", ", " }, StringSplitOptions.RemoveEmptyEntries);

                if (tokens[0] == "Push")
                {

                    //stack.Push(tokens.Skip(1)
                    //    .Select(t => t.Split(',').First())
                    //    .ToArray());

                    foreach (var item in tokens.Skip(1))
                    {
                        stack.Push(int.Parse(item));
                    }
                }
                else if (tokens[0] == "Pop")
                {
                    try
                    {
                        stack.Pop();
                    }
                    catch (ArgumentException ae)
                    {
                        Console.WriteLine(ae.Message);

                    }
                }

                commandInput = Console.ReadLine();
            }

            foreach (int element in stack)
            {
                Console.WriteLine(element);

            }

            foreach (int element in stack)
            {
                Console.WriteLine(element);
            }
        }
    }
}