#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  pair<int, int> p[n];
  int t = 0;
  for (int i = 0; i < n; i++) {
    cin >> p[i].first >> p[i].second;
  }
  sort(p, p + n);
  int start = 0, l = 0, r = 0, s = 0;
  for (int i = 0; i < 2 * n; i++) {
    if (i < n && p[i].first > 0) {
      start = 1;
    }
    if (start) {
      l = i - 1;
      r = i;
      while (1) {
        if (l < 0 && r == n) break;
        if (l < 0) {
          s += p[r].second;
          break;
        } else if (r == n) {
          s += p[l].second;
          break;
        }
        s += p[l--].second + p[r++].second;
      }
      return cout << s, 0;
    }
  }
  cout << p[n - 1].second << endl;
  return 0;
}
