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()
      |> (fn [t, s] -> {t |> String.to_integer(), s} end).()
    end)
    |> solve
    |> IO.puts()
  end

  def solve(t) do
    solve_rec(t, [])
  end

  def solve_rec([], r) do
    r |> Enum.join()
  end

  def solve_rec([{t, s} | l], r) do
    case t do
      0 -> solve_rec(l, r |> List.insert_at(-1, s))
      1 -> solve_rec(l, [s | r])
    end
  end
end