#include <bits/stdc++.h>
using namespace std;
#define ll long long
int main() {
ios::sync_with_stdio(false); cin.tie(nullptr);
int n;
cin >> n;
pair<ll, ll> p[n + 1];
for (int i = 1; i <= n; i++) {
cin >> p[i].first >> p[i].second;
}
sort(p + 1, p + n + 1);
vector<ll> ps(n + 1);
for (int i = 1; i <= n; i++) {
ps[i] = ps[i - 1] + p[i].second;
}
multiset<ll> s;
for (int i = 1; i <= n; i++) {
s.insert(ps[i] - p[i].first);
}
ll ans = 0;
for (int i = 1; i <= n; i++) {
if (i != 1) {
s.erase(s.find(ps[i - 1] - p[i - 1].first));
}
ans = max(ans, *s.rbegin() - ps[i - 1] + p[i].first);
}
cout << ans;
}
