#include <iostream>
#include <vector>
#include <queue>
#include <algorithm>
#include <fstream>
using namespace std;
typedef long long ll;
int main() {

    int n;
    cin >> n;

    vector<pair<ll, ll>> v(n);
    for(int i = 0; i < n; i++) {
        cin >> v[i].second >> v[i].first;
    }
    sort(v.begin(), v.end());
    int i = 0, j = n - 1;
    ll res = 0;
    int L = 0, R = 0;
    while(i <= j) {
        res = max(res, v[i].first + v[j].first);
        L++;
        R++;

        if(L > v[i].second) {
            i++;
            L = 0;
        }
        if(R > v[j].second) {
            j--;
            R = 0;
        }
    }
    cout << res << endl;

    return 0;
}