Sub Modif_format()
Dim i As Integer
Application.ScreenUpdating = False
For i = 19 To 3000 Step 1
If Cells(i, 5).Value = Cells(i + 1, 5).Value And Cells(i, 3) = Cells(i + 1, 3) Then
Cells(i, 2) = Cells(i, 2) & "," & Cells(i + 1, 2)
Rows(i + 1).Delete
End If
Next i
Application.ScreenUpdating = True
End Sub