As the length is only 2.75 meter , I have a problem and I am going to waste a lot of wood. K. prapoch calculation are right, we now need 40 and not 30.
Can you please can the seller and ask him to change for wood (34 pieces in fact as on the , some I bought before) that is 3 meters long.
If he can't no need no need to get longer wood (same problem, I will lose 55 cm each time), please ask him to deliver 5 more pieces so that the work can be done. I will pay even if I am not happy that he sells 2.75 meters long saying it is 3 meters.