#include <bits/stdc++.h> using namespace std; typedef long long ll; int main() { ios::sync_with_stdio(0); cout.tie(0); cin.tie(0); ll n; cin >> n; multiset<pair<ll, ll>> s; vector<pair<ll, ll>> v; for (ll i = 0; i < n; i++) { ll a, b; cin >> a >> b; s.insert({a, b}); v.push_back({a, b}); } sort(v.begin(), v.end()); ll l, sum, ans; l = sum = ans = 0; for (auto [a, b] : v) { l = min(l, sum - a); sum += b; ans = max(ans, sum - a - l); } cout << ans; }