static void Main(string[] args)
{
string input = Console.ReadLine();
CustomStack <string> collections = new CustomStack <string>();
while (input != "END")
{
string[] token = input.Split(new[] { ',', ' ' }, StringSplitOptions.RemoveEmptyEntries).ToArray();
switch (token[0])
{
case "Push":
{
collections.Push(token);
}
break;
case "Pop":
{
collections.Pop();
}
break;
}
input = Console.ReadLine();
}
collections.Collections.Reverse();
foreach (var element in collections.Collections)
{
Console.WriteLine(element);
}
foreach (var element in collections.Collections)
{
Console.WriteLine(element);
}
}