#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const int N = 5e5 + 24;
const ll INF = 1e18;
int n; pair<ll, ll> a[N];
ll pf[N];
void solve() {
cin >> n;
for (int i = 1; i <= n; i++) {
cin >> a[i].first >> a[i].second;
}
sort(a + 1, a + n + 1);
for (int i = 1; i <= n; i++) {
pf[i] = pf[i - 1] + a[i].second;
}
ll mn = INF, res = -INF;
for (int i = 1; i <= n; i++) {
mn = min(mn, pf[i - 1] - a[i].first);
res = max(res, pf[i] - a[i].first - mn);
}
cout << res << '\n';
}
int main() {
cin.tie(0) -> sync_with_stdio(0);
int T = 1; // cin >> T;
while (T--) {
solve();
}
}
