#include <iostream>
#include <vector>
#include <algorithm>
#include <climits>
using namespace std;
struct Artwork {
long long size;
long long value;
};
bool compareArtworks(const Artwork& a, const Artwork& b) {
return a.size < b.size;
}
int main() {
int n;
cin >> n;
vector<Artwork> artworks(n);
for (int i = 0; i < n; ++i) {
cin >> artworks[i].size >> artworks[i].value;
}
sort(artworks.begin(), artworks.end(), compareArtworks);
vector<long long> prefix_sums(n + 1, 0);
for (int i = 0; i < n; ++i) {
prefix_sums[i + 1] = prefix_sums[i] + artworks[i].value;
}
long long max_diff = LLONG_MIN;
long long prefix_min = LLONG_MAX;
for (int r = 0; r < n; ++r) {
prefix_min = min(prefix_min, prefix_sums[r] - artworks[r].size); // P[l-1] - A[l]
max_diff = max(max_diff, (prefix_sums[r + 1] - artworks[r].size) - prefix_min); // (P[r] - A[r]) - min(P[l-1] - A[l])
}
cout << max_diff << endl;
return 0;
}
