Вычислить значение выражения - VB (58731)

Sub ffd()
Dim a As Double, c As Integer, p As Integer, z As Double, y As Double
c = -38
p = 18
a = InputBox("Enter a", a)
y = Sin(a) + Sqr(p)
If y < 0 Then
z = (y / 5.5) + Sqr((a + c) ^ 3)
End If
If y > 0 Then
z = (7.3 * c) / y
End If
MsgBox (z)
End Sub