#include <bits/stdc++.h>
using namespace std;
#define int long long
signed main () {
int n;
cin >> n;
vector <pair <int, int>> arr(n + 1);
arr[0] = {0, 0};
for (int i = 1; i <= n; i++) cin >> arr[i].first >> arr[i].second;
sort(arr.begin(), arr.end());
for (int i = 1; i <= n; i++) arr[i].second += arr[i - 1].second;
int sum = -1e18;
int l = 1;
for (int r = 1; r <= n; r++) {
if (arr[r].first - arr[l].first > arr[r].second - arr[l - 1].second) l = r;
sum = max(sum, -1 * arr[r].first + arr[l].first + arr[r].second - arr[l - 1].second);
}
cout << sum << endl;
}
