defmodule Main do
  def main do
    1..(IO.read(:line)
        |> String.trim()
        |> String.to_integer())
    |> Enum.map(fn _ ->
      IO.read(:line)
      |> String.trim()
      |> String.split()
    end)
    |> solve_rec([], [])
    |> IO.puts()
  end

  def solve_rec([], l, r) do
    (l |> Enum.join()) <> (r |> Enum.join() |> String.reverse())
  end

  def solve_rec([[t, s] | a], l, r) do
    case t do
      "0" -> solve_rec(a, l, [s | r])
      "1" -> solve_rec(a, [s | l], r)
    end
  end
end