#include <bits/stdc++.h>
using namespace std;
#define int long long
signed main () {
int n;
cin >> n;
vector <pair <int, int>> arr(n + 1);
for (int i = 1; i <= n; i++) cin >> arr[i].first >> arr[i].second;
sort(arr.begin() + 1, arr.end());
for (int i = 2; i <= n; i++) {
arr[i].second += arr[i - 1].second;
}
priority_queue <int, vector <int>, greater <int>> pq;
int ans = arr[1].second;
pq.push(-1 * arr[1].first);
for (int i = 2; i <= n; i++) {
ans = max(ans, arr[i].second - arr[i].first - pq.top());
ans = max(ans, arr[i].second - arr[i - 1].second);
pq.push(arr[i - 1].second - arr[i].first);
}
cout << ans << endl;
}
