main :-
    open('../data/2015/1/input.txt',read,InStream),
    get_char(InStream,NextChar),
    navigateStairs(NextChar, InStream, 0).

navigateStairs(end_of_file, _, Floor) :- 
    Floor.
navigateStairs(40, InStream, Floor) :- % opening paren
    get_char(InStream,NextChar),
    navigateStairs(NextChar, InStream, Floor + 1).
navigateStairs(41, InStream, Floor) :- % closing paren
    get_char(InStream,NextChar),
    navigateStairs(NextChar, InStream, Floor - 1).