1. (2017高一上·台州期末) 现有如下Visual Basic程序段：

Private Sub Command1_Click()

    Dim a , b , c  as Integer

    a = 27: b = 9: c = -6

    If a > b And b > 0 Then

        If c < 0 Then a = a - c Else a = a - b

    Else

        a = b + c

    End If

    Print a

End Sub

该程序段运行之后，变量a的值为。