#include "bits/stdc++.h"
using namespace std;
using ll = long long;
using pii = pair<int, int>;
int main() {
cin.tie(0)->sync_with_stdio(0);
int n;
cin >> n;
vector<pair<ll, ll>> a(n + 5);
for (int i = 1; i <= n; i++) {
ll tmp, tmp2;
cin >> tmp >> tmp2;
a[i] = make_pair(tmp, tmp2);
}
sort(a.begin() + 1, a.begin() + n + 1);
vector<ll> p(n + 5);
for (int i = 1; i <= n; i++) {
p[i] = p[i - 1] + a[i].second;
}
ll ans = 0;
ll tmp = 0;
//p[r] - p[l - 1] - (a[r] - a[l])
for (int i = 1; i <= n; i++) {
tmp = max(tmp, -p[i - 1] + a[i].first);
ans = max(ans, p[i] - a[i].first + tmp);
}
cout << ans << endl;
}
