:- use_module(library(lists), [last/2]).
:- use_module(contestlib, [sublist/2]).

close_valves(Valves) :-
	setof((N-Valves),valves_activefaucets(Valves,N),L),
	last(L,N-Valves).

valves_activefaucets(Valves,N) :-
	setof(valve(A,B),valve(A,B),AllValves),
	dripping(Drip),
	sublist(AllValves,Valves),
	\+ gets_water(Drip,Valves),
	findall(Faucet,(faucet(Faucet),gets_water(Faucet,Valves)),Faucets),
	length(Faucets,N).