#include "bits/stdc++.h"
using namespace std;

signed main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int n;
    cin >> n;

    vector<int> a(n);
    vector<int> b(n);

    for (int i = 0; i < n; i++) {
        cin >> a[i];
        cin >> b[i];
    }

    vector<int> c(n);
    iota(c.begin(), c.end(), 0);

    sort(c.begin(), c.end(), [&a](int i, int j) {
        return a[i] < a[j];
    });

    int cnt = 0;
    int sum = 0;

    for (int i : c) {
        if (a[i] > cnt) {
            sum += b[i];
        } 
        cnt += 1;
    }
    
    cout << sum << '\n';
    return 0;
}