-module(fish).
-export([fish/2]).

fish(A, B) ->
    Pairs = lists:zip(A, B),
    {_, Dead} = lists:foldl(fun({Ai, Bi}, {Stack, D}) ->
        case Bi of
            1 -> {[Ai | Stack], D};
            _ -> fight(Ai, Stack, D)
        end
    end, {[], 0}, Pairs),
    length(A) - Dead.

fight(_Ai, [], Dead) ->
    {[], Dead};
fight(Ai, [Top | Rest], Dead) ->
    Dead1 = Dead + 1,
    case Ai > Top of
        true -> fight(Ai, Rest, Dead1);
        false -> {[Top | Rest], Dead1}
    end.