get_number(Number) :-
    get_string(String),
    number_string(Number, String).

get_string(String) :-
    current_input(Input),
    read_string(Input, ' \n', '', _, String).

/* memo
    code(int)
    string_code(1, S, C), (C: code)
    char_code(X, Y) (X: char, Y: code)
    string_chars(S, S2) (S: string, S2: [char])
    to_lower(C, C2) (C: char? C2: code?)

    f(0, [], []).
    f(Z, [X|Xs], [Y|Ys]) :- X = Y, f(Z1, Xs, Ys), Z is Z1 + 1.
    f(Z, [_|Xs], [_|Ys]) :- f(Z, Xs, Ys).

    match: =, \=

    numeric: <,=<, >, >= (eval)
    lexicographically: @<. @=<, @>, @>=
    value?: =:=, =\= (eval)
    identical: ==, \==
*/

f(0, []) :- !.
f(X, ['+'|Cs]) :- f(X2, Cs), X is X2 + 1, !.
f(X, ['-'|Cs]) :- f(X2, Cs), X is X2 - 1, !.

main :-
	get_string(S),
    f(X, S),
    writeln(X).
