start :-
    input(Input),
    maplist(predict, Input, Ps),
    sum_list(Ps, Answer),
    writef('Answer=%t\n', [Answer]).

predict(L, 0) :- maplist(=:=(0), L), !.
predict(L, X) :-
    foldl([Li1, Li2, C, D]>>(Li2 is Li1 - C, D = Li1), L, [_ | NewL], 0, _),
    predict(NewL, SubX),
    L = [L1 | _], X is L1 - SubX.