C. Timbre

Petru gaseste o scrisoare in cutia postala. Isi aduce aminte ca Posta Romana doreste sa introduca timbre de valori noi astfel incat lipind maxim 3 timbre pe o scrisoare sa se poata obtine orice valoare intreaga de la 1 la 15 RON. Ce valori trebuie sa aiba timbrele, daca se doreste introducea unui numar minim de timbre de valori diferite?

Sursa: adaptare (Ruxandra F. Olimid, dupa o problema cunoscuta)

C. Stamps

Petru finds a letter in the mailbox. He remembers that the Romanian Post Office plans to introduce new value stamps so that sticking maximum 3 stamps on a letter, one can get any value in RON from 1 to 15. What values should the stamps have, if it is desired to introduce a minimum number of different values?

Source: adaptation (Ruxandra F. Olimid) on a classic problem