#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
struct Artwork {
long long size;
long long value;
};
long long maximizeArtExhibition(int N, vector<Artwork>& artworks) {
sort(artworks.begin(), artworks.end(), [](const Artwork& a, const Artwork& b) {
return a.size < b.size;
});
long long maxSMinusDiff = 0;
long long totalValue = 0;
long long A_min = artworks[0].size;
for (int i = 0; i < N; ++i) {
long long A_max = artworks[i].size;
totalValue += artworks[i].value;
long long currentSMinusDiff = totalValue - (A_max - A_min);
maxSMinusDiff = max(maxSMinusDiff, currentSMinusDiff);
}
return maxSMinusDiff;
}
int main() {
int N;
cin >> N;
vector<Artwork> artworks(N);
for (int i = 0; i < N; ++i) {
cin >> artworks[i].size >> artworks[i].value;
}
long long result = maximizeArtExhibition(N, artworks);
cout << result << endl;
return 0;
}
