Private Sub Worksheet_Change(ByVal Target As Range)
On Error GoTo Chyba
Application.EnableEvents = False
    If (Target.Column <> 1 _
        And Target.Column <> 7 _
        And Target.Column <> 8 _
        And Target.Column <> 9 _
        And Target.Column <> 15) _
        Or Target.Row < 10 Or Target = "" Then
        Application.EnableEvents = True
        Exit Sub
    End If
    If Target.Row < 50 Then
        Storoc = 19
        Else: Storoc = 20
    End If
    Target = Left(Target, 2) & "." & Mid(Target, 3, 2) & "." & Storoc & Right(Target, 2)
    Application.EnableEvents = True
    Exit Sub
Chyba:
    Application.EnableEvents = True
    Exit Sub
End Sub