
Module Program

    Sub Main(args As String())

        Dim arrStr As String() = Split(Console.ReadLine())
        Dim Taka_HP As Integer = CInt(arrStr(0))
        Dim Taka_AP As Integer = CInt(arrStr(1))
        Dim Ao_HP As Integer = CInt(arrStr(2))
        Dim Ao_AP As Integer = CInt(arrStr(3))

        Dim taka_turn As Boolean = True
        While Taka_HP > 0I And Ao_HP > 0I
            If taka_turn = True Then
                Ao_HP = Ao_HP - Taka_AP
                taka_turn = False
            Else
                Taka_HP = Taka_HP - Ao_AP
                taka_turn = True
            End If
        End While

        If Taka_HP <= 0I Then
            Console.WriteLine("No")
        Else
            Console.WriteLine("Yes")
        End If

    End Sub

End Module