#include <bits/stdc++.h>
using i64 = long long int;
int main(void) {
std::ios_base::sync_with_stdio(0);
std::cin.tie(nullptr);
int n; std::cin >> n;
std::vector <i64> a(n + 1), b(n + 1);
for (int i = 1; i <= n; i += 1) {
std::cin >> b[i] >> a[i];
}
std::vector <int> ord(n + 1); std::iota(ord.begin(), ord.end(), 0);
std::sort(ord.begin() + 1, ord.end(), [&] (int i, int j) -> bool { return b[i] < b[j]; });
std::vector <i64> p(n + 1);
for (int i = 1; i <= n; i += 1) {
p[i] = p[i - 1] + a[ord[i]];
}
i64 ans = 0;
i64 mi = p[0] - b[ord[1]];
for (int i = 1; i <= n; i += 1) {
ans = std::max(ans, p[i] - b[ord[i]] - mi);
if (i + 1 <= n)
mi = std::min(mi, p[i] - b[ord[i + 1]]);
}
std::cout << ans << '\n';
return 0^0;
}
