#include <bits/stdc++.h>

using namespace std;

struct Node {
    int l, r;
    bool operator< (const Node &t) const {
        return l + r < t.l + t.r;
    }
};

int n;
vector<Node> a;

int main(void) {
    cin >> n;
    for (int i = 0; i < n; ++i) {
        int w, s;
        cin >> w >> s;
        a.push_back({w, s});
    }

    sort(a.begin(), a.end());

    int res = -2e9;
    int sum = 0;
    for (auto [w, s] : a) {
        res = max(sum - s, res);
        sum += w;
    }

    cout << res;
    return 0;

}