import Enum

defmodule Main do
  def battle(a, _b, c, _d) when a <= 0 or c <= 0 do
    if c > 0 do
      "No"
    else
      "Yes"
    end
  end

  def battle(a, b, c, d) do
    battle(a - d, b, c - b, d)
  end

  def main do
    [a, b, c, d] =
      IO.read(:line)
      |> String.trim
      |> String.split(" ")
      |> map(&String.to_integer(&1))

    IO.puts(battle(a, b, c, d))
  end
end
