static void Main(string[] args)
{
string[] input = Console.ReadLine().Split(new char[] { ',', ' ' }, StringSplitOptions.RemoveEmptyEntries).Skip(1).ToArray();
CustomStack <string> stack = new CustomStack <string>(input);
while (true)
{
try
{
string command = Console.ReadLine();
if (command == "Pop")
{
stack.Pop();
}
string[] inputargs = command.Split();
if (inputargs[0] == "Push")
{
stack.Push(inputargs[1]);
}
if (command == "END")
{
IEnumerable <string> final = stack.Reverse();
foreach (var item in final)
{
Console.WriteLine(item);
}
foreach (var item in final)
{
Console.WriteLine(item);
}
break;
}
}
catch (InvalidOperationException io)
{
Console.WriteLine(io.Message);
}
}
}