当下列程序运行，单击窗体后，分别输入72和24，信息框上显示的结果是______。
Private Sub Form_Click( )
Dim x As Integer， y As Integer
x = Val(InputBox("输入整数72"))
y = Val(InputBox("输入整数24"))
z = fun1(x， y)
MsgBox Str(z)
End Sub
Private Function fun1(ByVal a As Integer， ByVal b As Integer)As Integer
Do
r = a Mod b
a = b
b = r
Loop Until r = 0
fun1 = a
End Function
