Maximize the Tax

Nikitas does not want to study for his exams, so he decided to become a disruptor and get a part-time job as a tax collector in Airland. Airland consists of $N$ houses (numbered $1$ through $N$) and $M$ one-way supply pathways that connect them. Each house has a budget; let's denote the budget of house $i$ by $B_i$ (in coins). The *neighbourhood* of a house is the set of houses which both can supp