单项选择题

下面程序：
Private Sub Form_Click()
Dim x,y,z As Integer
x=5
y=7
z=0
CallPI(x,y,z)
Print Str(z)
End Sub
SubP1(By Val a As Integer, By Val b As Integer, c As Integer)
C=a+b
End Sub
运行后的输出结果为______。