#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
using ll = long long;
vector <pair <ll, ll>> pnts;
int main() {
int n;
cin >> n;
pnts.resize(n+1);
for (int i = 1; i <= n; i++)
cin >> pnts[i].first >> pnts[i].second;
sort(pnts.begin() + 1, pnts.end());
for (int i = 2; i <= n; i++)
pnts[i].second += pnts[i-1].second;
ll ans = pnts[1].second;
int l = 1, r = 1;
for (int i = 2; i <= n; i++) {
ans = max(ans, pnts[i].second - pnts[i-1].second);
ll added_diff = pnts[i].first - pnts[r].first;
ll added_val = pnts[i].second - pnts[r].first;
if (added_val >= added_diff) {
ans = max(ans, (pnts[i].second - pnts[l-1].second) - (pnts[i].first - pnts[l].first));
r = i;
} else if (l+1 <= r) {
added_diff -= (pnts[l+1].first - pnts[l].first);
added_val -= (pnts[l].second - pnts[l-1].second);
if (added_val >= added_diff) {
ans = max(ans, (pnts[i].second - pnts[l].second) - (pnts[i].first - pnts[l+1].first));
l++;
}
}
}
cout << ans << '\n';
}
