#include <iostream>
#include <fstream>
#include <queue>
#include <tuple>
#include <cmath>
#include <algorithm>
#include <vector>
#define int long long

using namespace std;


bool sortbysecond(tuple<int, int, int>& a, tuple<int, int, int>& b) {
    return get<1>(a) < get<1>(b);
}

int binSearch(int start, int end, int number, vector<tuple<int, int, int>>& vect) {

    while (start != end) {
        int mid = (start + end + 1) / 2;

        if ((get<1>(vect[mid])) <= number) {
            start = mid;
        }
        else {
            end = mid - 1;
        }
    }

    return start;

}


main() {

    ifstream in("convention2.in");
    ofstream out("convention2.out");


    int N;
    in >> N;

    vector <tuple<int, int, int>> vals = {};
    priority_queue<tuple<int, int, int>, vector<tuple<int, int, int>>, greater<tuple<int, int, int>>> pq = {};


    for (int i = 1; i <= N; i++) {
        int b, c;
        in >> b >> c;
        vals.push_back(make_tuple(i, b, c));
    }

    sort(vals.begin(), vals.end(), sortbysecond);

    int pointer = 1;
    int prevfinishing = get<1>(vals[0]) + get<2>(vals[0]);
    int highestIndex = binSearch(pointer, N - 1, prevfinishing, vals);

    for (int i = pointer; i <= highestIndex; i++) {
        pq.push(vals[i]);
    }

    int maxwait = 0;
    int wait = 0;
    int arrivaltime = get<1>(vals[0]);
    pointer = highestIndex + 1;
    while (pointer < N) {

        int wait = prevfinishing - get<1>(pq.top());
        prevfinishing = max(prevfinishing + get<2>(pq.top()), get<1>(pq.top()) + get<2>(pq.top()));
        maxwait = max(wait, maxwait);
        pq.pop();
        highestIndex = binSearch(pointer, N - 1, prevfinishing, vals);
        for (int i = pointer; i <= highestIndex; i++) {
            pq.push(vals[i]);
        }

        pointer = highestIndex + 1;
    }

    while (!pq.empty()) {
        int wait = prevfinishing - get<1>(pq.top());
        prevfinishing = prevfinishing + get<2>(pq.top());
        maxwait = max(wait, maxwait);
        pq.pop();
    }

    out << maxwait;







    return 0;
}