How to trim string(s)/URL(s) to last folder?

http://www.site.com/folder1/folder2/
http://www.site.com/folder1/folder2/234/
http://www.site.com/folder2/folder2/sagdg
http://www.site.com/folder2/folder4/fdgdf

http://www.site.com/folder1/
http://www.site.com/folder2/

Imports System.Text.RegularExpressions

Public Class Form1

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

        For Each xlink In RichTextBox1.Lines                 ' Replace xx with tt
            Dim MC As MatchCollection = Regex.Matches(xlink, "hxxp://(.*?)/(.*?)/")
            For Each m As Match In MC
                Dim g1 As Group = m.Groups(1)
                Dim g2 As Group = m.Groups(2)
                                    ' Replace xx with tt
                ListBox1.Items.Add("hxxp://" & g1.ToString & "/" & g2.ToString & "/")
            Next
        Next

    End Sub

End Class