过程代码段如下，单击Button1后，文本框中显示的结果是______。
    Private Sub p(ByVal a As Integer)
        a = a + 1
    End Sub
    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        Dim n, s, x As Integer
        s = 0
        x = 1
        For n = 1 To 5
            Call p(x)
            s = s + x
        Next
        TextBox1.Text = s
    End Sub