#include <iostream>
#include <vector>
#include <algorithm>
int main() {
int n;
std::cin >> n;
std::vector<std::pair<long long, long long>> arts(n);
for (auto& [a, b] : arts) std::cin >> a >> b;
std::ranges::sort(arts);
long long ans = 0;
long long b_sum = 0;
long long min_diff = -arts[0].first;
for (int i = 0; i < n; ++i) {
// prefix sum i - prefix sum j-1 - arts[i].a + arts[j].a, j = 0 ~ i
min_diff = std::min(min_diff, b_sum - arts[i].first);
b_sum += arts[i].second;
ans = std::max(ans, b_sum - arts[i].first - min_diff);
}
std::cout << ans << "\n";
}
