Dim x_coords(1 To 10) As Single
Dim y_coords(1 To 10) As Single
Dim i, k As Integer
Dim z(1 To 2) As Single
Dim z_(1 To 2) As Single
Private Sub Form_Load()
    Form1.Scale (-1000, 1000)-(1000, -1000)
    i = 1
End Sub
Private Sub Form_MouseDown(Button As Integer, Shift As Integer, x As Single, y As Single)
    If Point(x, y) = vbBlack Then
        k = k + 1
        For q = 1 To 10
            If x_coords(q) = x Then
                z(k) = x_coords(q)
                z_(k) = y_coords(q)
            End If
        Next q
    End If
    If (i <= 10 And Point(x, y) <> vbBlack) Then
        x_coords(i) = x
        y_coords(i) = y
        FillStyle = vbSolid
        FillColor = vbBlack
        Circle (x_coords(i), y_coords(i)), 10
        i = i + 1
    End If
    If (k = 2) Then
        Line (z(1), z_(1))-(z(2), z_(2))
        k = 0
    End If
End Sub