#include <bits/stdc++.h>
using namespace std;
string DBG_DLM(int &i) { return (i++ == 0 ? "" : ", "); }
template <class T>
ostream &operator<<(ostream &os, vector<T> v);
template <class T>
ostream &operator<<(ostream &os, set<T> v);
template <class T>
ostream &operator<<(ostream &os, queue<T> q);
template <class T>
ostream &operator<<(ostream &os, priority_queue<T> q);
template <class T, class K>
ostream &operator<<(ostream &os, pair<T, K> p);
template <class T, class K>
ostream &operator<<(ostream &os, map<T, K> mp);
template <class T, class K>
ostream &operator<<(ostream &os, unordered_map<T, K> mp);
template <int I, class TPL>
void DBG(ostream &os, TPL t) {}
template <int I, class TPL, class H, class... Ts>
void DBG(ostream &os, TPL t) {
  os << (I == 0 ? "" : ", ") << get<I>(t);
  DBG<I + 1, TPL, Ts...>(os, t);
}
template <class T, class K>
void DBG(ostream &os, pair<T, K> p, string delim) {
  os << "(" << p.first << delim << p.second << ")";
}
template <class... Ts>
ostream &operator<<(ostream &os, tuple<Ts...> t) {
  os << "(";
  DBG<0, tuple<Ts...>, Ts...>(os, t);
  os << ")";
  return os;
}
template <class T, class K>
ostream &operator<<(ostream &os, pair<T, K> p) {
  DBG(os, p, ", ");
  return os;
}
template <class T>
ostream &operator<<(ostream &os, vector<T> v) {
  {
    int i = 0;
    os << "{";
    {
      for (auto &&t : v) {
        os << DBG_DLM(i) << t;
      };
    }
    os << "}";
    return os;
  };
}
template <class T>
ostream &operator<<(ostream &os, set<T> s) {
  {
    int i = 0;
    os << "{";
    {
      for (auto &&t : s) {
        os << DBG_DLM(i) << t;
      };
    }
    os << "}";
    return os;
  };
}
template <class T>
ostream &operator<<(ostream &os, queue<T> q) {
  {
    int i = 0;
    os << "{";
    {
      for (; q.size(); q.pop()) {
        os << DBG_DLM(i) << q.front();
      };
    }
    os << "}";
    return os;
  };
}
template <class T>
ostream &operator<<(ostream &os, priority_queue<T> q) {
  {
    int i = 0;
    os << "{";
    {
      for (; q.size(); q.pop()) {
        os << DBG_DLM(i) << q.top();
      };
    }
    os << "}";
    return os;
  };
}
template <class T, class K>
ostream &operator<<(ostream &os, map<T, K> m) {
  {
    int i = 0;
    os << "{";
    {
      for (auto &&p : m) {
        os << DBG_DLM(i);
        DBG(os, p, "->");
      };
    }
    os << "}";
    return os;
  };
}
template <class T, class K>
ostream &operator<<(ostream &os, unordered_map<T, K> m) {
  {
    int i = 0;
    os << "{";
    {
      for (auto &&p : m) {
        os << DBG_DLM(i);
        DBG(os, p, "->");
      };
    }
    os << "}";
    return os;
  };
}
using ll = long long;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
using pil = pair<int, ll>;
using pli = pair<ll, int>;
using vs = vector<string>;
using vvs = vector<vs>;
using vvvs = vector<vvs>;
using vb = vector<bool>;
using vvb = vector<vb>;
using vvvb = vector<vvb>;
using vi = vector<int>;
using vvi = vector<vi>;
using vvvi = vector<vvi>;
using vl = vector<ll>;
using vvl = vector<vl>;
using vvvl = vector<vvl>;
using vd = vector<double>;
using vvd = vector<vd>;
using vvvd = vector<vvd>;
using vpii = vector<pii>;
using vvpii = vector<vpii>;
using vvvpii = vector<vvpii>;
template <class A, class B>
bool amax(A &a, const B &b) {
  return b > a ? a = b, 1 : 0;
}
template <class A, class B>
bool amin(A &a, const B &b) {
  return b < a ? a = b, 1 : 0;
}
ll ri() {
  ll l;
  cin >> l;
  return l;
}
string rs() {
  string s;
  cin >> s;
  return s;
}
void Main() {
  int n = ri();
  ll a0 = ri();
  vector<int> A(n - 1);
  vector<char> ops(n - 1);
  for (int i = int(0); i < int(n - 1); ++i) {
    cin >> ops[i] >> A[i];
  };
  ;
  ll inf = 1e18;
  vvl minp(n - 1, vl(n, +inf));
  vvl maxp(n - 1, vl(n, -inf));
  for (int i = int(0); i < int(n - 1); ++i) {
    int v = A[i];
    minp[i][i + 1] = v;
    maxp[i][i + 1] = v;
  }
  function<ll(int, int)> fmin, fmax;
  fmax = [&](int l, int r) -> ll {
    if (r <= l) return 0;
    ll &ret = maxp[l][r];
    if (ret != -inf) return ret;
    if (ops[l] == '+') {
      ret = A[l] + fmax(l + 1, r);
    } else {
      for (int p = int(l + 1); p < int(r + 1); ++p) {
        ll cand = -fmin(l, p) + fmax(p, r);
        amax(ret, cand);
      }
    };
    return ret;
  };
  fmin = [&](int l, int r) -> ll {
    if (r <= l) return 0;
    ll &ret = minp[l][r];
    if (ret != +inf) return ret;
    ll head = A[l];
    if (ops[l] == '+') {
      ret = head + fmin(l + 1, r);
    } else {
      for (int p = int(l + 1); p < int(r + 1); ++p) {
        if (ops[p] == '+') {
          ll cand = head + fmin(l + 1, p) + fmin(p, r);
          amin(ret, cand);
        } else {
          ll cand = head + fmin(l + 1, p) - fmax(p, r);
          amin(ret, cand);
        }
      }
    };
    return ret;
  };
  ll ans;
  ans = a0 + fmax(0, n - 1);
  for (int l = int(0); l < int(n - 1); ++l)
    ;
  for (int l = int(0); l < int(n - 1); ++l)
    ;
  cout << ans << endl;
}
signed main() {
  cin.tie(nullptr);
  ios::sync_with_stdio(false);
  Main();
  return 0;
}
