Private Sub Worksheet_BeforeDoubleClick(ByVal Target As Range, Cancel As Boolean)
Dim i as Long
For i = 6 To 26
If Cells(i, 1) = "" Then
Cells(i, 2) = "N"
Cells(i, 2).Interior.Color = vbRed
t = Timer + 1: Do Until Timer > t: DoEvents: Loop
End If
Next i
Cancel = True
End Sub