#include <bits/stdc++.h>
using namespace std;
const long long INF =1e18;
int main() {
cin.tie(0)->sync_with_stdio(0);
int n;
cin>> n;
vector<pair<long long, long long>> a;
for (int i=0; i<n; i++) {
long long A, B;
cin>> A>> B;
a.push_back({A, B});
}
sort(a.begin(), a.end());
vector<long long> p(n+1, 0);
for (int i=n-1; i>=0; i--) p[i] = p[i+1]+a[i].second;
long long mx = 0, ans=-INF;
for (int i=0; i<n; i++) {
mx = max(mx, a[i].first+p[i]);
ans = max(ans, -a[i].first + mx - p[i+1]);
}
cout<< ans;
}
