import Enum

defmodule Main do
  def main do
    [s, w] =
      IO.read(:line)
      |> String.trim
      |> String.split(" ")
      |> map(&String.to_integer(&1))

    out =
      if s > w do
        "safe"
      else
        "unsafe"
      end

    IO.puts(out)
  end
end
