NOT (A OR B) <=> NOT-A AND NOT-B
* *
A B AorB not(AorB) not(A) not(B) not(A)andnot(B) T T T F F F F T F T F F T F F T T F T F F F F F T T T T
if numero >=1: stampa la tabellina else: stampa errore
if not numero >=1: stampa errore else: stampa la tabellina