#include <iostream>
#include <vector>
#include <algorithm>
#include <climits>
using namespace std;
int main() {
int n;
cin >> n;
vector<pair<long long, long long>> artworks(n);
for (int i = 0; i < n; ++i) {
cin >> artworks[i].first >> artworks[i].second; // {size, value}
}
sort(artworks.begin(), artworks.end());
vector<long long> prefix(n + 1, 0);
for (int i = 0; i < n; ++i) {
prefix[i + 1] = prefix[i] + artworks[i].second;
}
long long max_diff = LLONG_MIN;
long long prefix_min = LLONG_MAX;
for (int r = 0; r < n; ++r) {
long long size_r = artworks[r].first;
prefix_min = min(prefix_min, prefix[r] - size_r);
max_diff = max(max_diff, (prefix[r + 1] - size_r) - prefix_min);
}
cout << max_diff << endl;
return 0;
}
