#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  int n;
  while (cin >> n) {
    int pos, val;
    multimap<int, int> mp1, mp2;
    while (n--) {
      cin >> pos >> val;
      pos < 0 ? mp1.insert(pair<int, int>(pos, val))
              : mp2.insert(pair<int, int>(pos, val));
    }
    int min_size = min(mp1.size(), mp2.size());
    multimap<int, int>::reverse_iterator it1 = mp1.rbegin();
    multimap<int, int>::iterator it2 = mp2.begin();
    long long ans = 0;
    for (int i = 0; i < min_size; ++i, ++it1, ++it2)
      ans += ((it1->second) + (it2->second));
    if (mp1.size() > mp2.size()) ans += (it1->second);
    if (mp1.size() < mp2.size()) ans += (it2->second);
    cout << ans << endl;
  }
  return 0;
}
