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 is_mma(a, a, b), do: a != b
  def is_mma(_, _, _), do: false

  def main do
    [a, b, c] = input() |> String.graphemes()

    yn(is_mma(a, b, c))
  end
end