Необходимо построить фрактал-лестницу

Public Class Form1
    Sub line(x1%, y1%, x2%, y2%, c%)
        If c < NumericUpDown5.Value Then Exit Sub
        Dim x1n, y1n, x2n, y2n As Int32
        Dim g As Drawing.Graphics = CreateGraphics()
        g.DrawLine(Pens.Black, x1, y1, x2, y1)
        g.DrawLine(Pens.Black, x2, y1, x2, y2)
        g.DrawLine(Pens.Black, x1n, y1n, x2n, y1n)
        g.DrawLine(Pens.Black, x2n, y1n, x2n, y2n)
        'Левый верхний угол
        line(x1, y1 / 2, 3 * x2 \ 4, y1 / 2, c / 2)
        line(x2, 3 * y2 / 4, 5 / 4 * x2, y2, c / 2)
        g.Dispose()
    End Sub
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Refresh()
        Dim x1, y1, x2, y2, size As Int32
        x1 = CInt(NumericUpDown1.Value)
        y1 = CInt(NumericUpDown2.Value)
        x2 = CInt(NumericUpDown3.Value)
        y2 = CInt(NumericUpDown4.Value)
        size = CInt(NumericUpDown6.Value)
        line(x1, y1, x2, y2, size)
    End Sub
End Class