Private Sub Worksheet_Change(ByVal Target As Range)
If Not Intersect(Target, Range("C5:C600")) Is Nothing Then
    With Application
        .EnableEvents = False
        On Error Resume Next
        .Undo
        .EnableEvents = True
    End With
End If
End Sub

Private Sub Worksheet_BeforeDoubleClick(ByVal Target As Range, Cancel As Boolean)
    If Not Intersect(Target, Range("C5:C600")) Is Nothing Then
        Application.EnableEvents = False
        Cancel = True
        If Target <> "" Then
            Target.ClearContents
        Else
            Target.Font.Name = "Marlett"
            Target = "a"
        End If
        Application.EnableEvents = True
    End If
End Sub
Private Sub Worksheet_Change(ByVal Target As Range)
    Set d0_ = Intersect(Target, Range("C5:C600"))
    If Not d0_ Is Nothing Then
        Application.ScreenUpdating = 0
        Application.Calculation = 3
        Application.EnableEvents = 0
        With Sheets("Табель")
            For Each d_ In d0_
                If d_.Value <> "" Then
                    d_.Value = "a"
                End If
                s_ = d_.Offset(, -1)
                Set dt_ = .Columns(3).Find(s_)
                If dt_ Is Nothing Then
                    If d_ <> "" Then
                        For i = 3 To 999 Step 11
                            If .Cells(i, 3) = "" Then
                    .Cells(i, 3).Value = s_
                    Exit For
                            End If
                        Next
                    End If
                Else
                    d_.ClearContents
                    dt_.ClearContents
                End If
            Next d_
        End With
        Application.EnableEvents = 1
        Application.Calculation = 1
        Application.ScreenUpdating = 1
    End If
End Sub