Class Main
    Public Shared Sub Main()
        Dim tmp As String() = Split(Console.ReadLine(), " ")
        Dim A As Integer = CInt(tmp(0))
        Dim B As Integer = CInt(tmp(1))
        Dim C As Integer = CInt(tmp(2))
    Dim D As Integer = CInt(tmp(3))
    if (A + d - 1) \ D >= (C + b - 1) \ B THEN
        Console.WriteLine("Yes")
      else
      Console.WriteLine("No")
        end if
        End Sub
End Class
