#!/usr/bin/env python3


def solve(n):

    s = input()
    sum_a = 0
    sum_n = 0
    sum_np = 0
    min_sum_np = 10 ** 15

    j = s.find('-')
    if j < 0:
        return sum(list(map(int, s.split(' + '))))

    sum_a = sum(list(map(int, s[:j - 1].split(' + '))))
    j += 2
    s += ' '
    len_s = len(s)
    sign = -1
    w = ''
    while j < len_s:
        ch = s[j]
        j += 1
        if ch == ' ':
            if len(w):
                a = int(w)
                sum_a += a
                w = ''
                if sign < 0:
                    sum_n += a
                    sum_np = 0
                else:
                    sum_np += a
        elif ch == '+':
            sign = 1
        elif ch == '-':
            min_sum_np = min(min_sum_np, sum_n + sum_np)
            sign = -1
        else:
            w += ch

    min_sum_np = min(min_sum_np, sum_n + sum_np)
    return sum_a - 2 * min_sum_np


def main():
    n = input()
    n = int(n)

    print(solve(n))


if __name__ == '__main__':
    main()

