public static void Main()
{
var data = new CustomStack <string>();
while (true)
{
var input = Console.ReadLine();
if (input == "END")
{
break;
}
if (input.Contains("Push"))
{
var elements = input.Split(new string[] { ", ", " " }, StringSplitOptions.RemoveEmptyEntries);
for (int i = 1; i < elements.Length; i++)
{
data.Add(elements[i]);
}
}
else
{
data.Remove();
}
}
for (int i = 0; i < 2; i++)
{
foreach (var value in data)
{
Console.WriteLine(value);
}
}
}