defmodule Main do
  def input, do: IO.read(:line) |> String.trim
  def ii, do: input() |> String.to_integer
  def li, do: input() |> String.split |> Enum.map(&String.to_integer/1)
  def yn(b), do: IO.puts(if b, do: "Yes", else: "No")

  def main do
    [n, wlimit] = li()

    for _ <- 1..n do
      [v, w] = li()
      {v, w}
    end
    |> Enum.filter(fn {_, w} -> w <= wlimit end)
    |> Enum.map(fn {v, _} -> v end)
    |> Enum.max(&>=/2, fn -> -1 end)
    |> IO.puts
  end
end