#include <bits/stdc++.h>
using namespace std;
template <class T>
bool chmax(T &a, const T &b) {
  if (a < b) {
    a = b;
    return 1;
  }
  return 0;
}
template <class T>
bool chmin(T &a, const T &b) {
  if (a > b) {
    a = b;
    return 1;
  }
  return 0;
}
template <class T>
ostream &operator<<(ostream &os, const vector<T> &t) {
  os << "[";
  for (__typeof((t).begin()) it = (t).begin(); it != (t).end(); it++) {
    if (it != t.begin()) os << ",";
    os << *it;
  }
  os << "]";
  return os;
}
template <class T>
ostream &operator<<(ostream &os, const set<T> &t) {
  os << "{";
  for (__typeof((t).begin()) it = (t).begin(); it != (t).end(); it++) {
    if (it != t.begin()) os << ",";
    os << *it;
  }
  os << "}";
  return os;
}
template <class S, class T>
ostream &operator<<(ostream &os, const pair<S, T> &t) {
  return os << "(" << t.first << "," << t.second << ")";
}
template <class S, class T>
pair<S, T> operator+(const pair<S, T> &s, const pair<S, T> &t) {
  return pair<S, T>(s.first + t.first, s.second + t.second);
}
template <class S, class T>
pair<S, T> operator-(const pair<S, T> &s, const pair<S, T> &t) {
  return pair<S, T>(s.first - t.first, s.second - t.second);
}
const int INF = 1 << 28;
const double EPS = 1e-8;
const int MOD = 1000000007;
int T, n, m;
int main(int argc, char *argv[]) {
  ios::sync_with_stdio(false);
  cin >> n;
  long long int sum = 0, ans = 1ll << 60, mins = 0, seq = 0, lastmins = 0;
  cin >> sum;
  for (int i = 0; i < (int)(n - 1); i++) {
    char op;
    long long int x;
    cin >> op >> x;
    sum += x;
    if (op == '-') {
      if (mins) {
        ans = min(ans, mins + seq - lastmins);
      }
      mins += x;
      lastmins = x;
    }
    seq += x;
  }
  ans = min(ans, mins);
  cout << sum - 2 * ans << endl;
  return 0;
}
