# https://yukicoder.me/problems/no/3210




def main():
    N = int(input())
    S = input()

    answer = 0
    # +のみ
    ans = 0
    for s in S:
        if s == "+":
            ans += 1
    answer = max(answer, ans)

    # - のみ　
    ans = 0
    for s in S:
        if s == "-":
            ans += 1
    answer = max(answer, ans)

    # 0 のみ
    if "0" in S:
        answer = max(answer, 1)
    
    # 混ぜる

    forward_minus_num_list = [0] * N
    f = 0
    for i in range(N):
        if S[i] == "-":
            f += 1
        forward_minus_num_list[i] = f
    backward_plus_num_list = [0] * N
    b = 0
    for i in reversed(range(N)):
        if S[i] == "+":
            b += 1
        backward_plus_num_list[i] = b

    for i in range(N):
        x = forward_minus_num_list[i] + backward_plus_num_list[i]
        if S[i] == "0":
            x += 1
        answer = max(answer, x)

    print(answer)

    









if __name__ == "__main__":
    main()