If Left(Range("A2"), 5) = "12345" Then Range("A1") = -1
Private Sub Worksheet_SelectionChange(ByVal Target As Range)
If Target.Column <> 2 Then Exit Sub
If Left(ActiveCell, 7) = "3661384" Then ActiveCell.Offset(0, -1).Value = ActiveCell.Offset(0, -1).Value - 1
End Sub