internal static Stack<string> CreateStack(string input)
{
var lines = input.Trim().Split(' ');
var stack = new Stack<string>(); // LIFO
for (var i = (lines.Length - 1); i >= 0; i--)
{
var line = lines[i];
if (!string.IsNullOrEmpty(line))
{
line = line.Trim();
stack.Push(line);
}
}
return stack;
}
