the number of cells which can be filled by elimination, starting from the blank grid (i.e. only a 2 can go in this box, so it must be a 2)
Eliminazioz bete daitezkeen laukien kopurua, hutsik dagoen saretatik hasiz (adibidez, koadro batean 2a soilik joan badaiteke, 2a izango da).