Тестовое задание

Brainy smurf suggested that Smurfs start using money and checks to transact, like humans. The only one who keeps tracking of those checks is himself, but someday he leaves the village and announces that he will return months later. All Smurfs trust Papa Smurf (and are considered to be trustworthy) and ask him how should they consider those checks until Brainy (the banker) returns. Papa Smurf might advise them that they should be considered: