#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int maxN = 5e5 + 2;
int n;
pair<ll, int> arr[maxN];
ll pfx[maxN], pre_min = numeric_limits<ll>::max(), ans;
int main() {
cin.tie(nullptr)->sync_with_stdio(false);
cin >> n;
for (int i = 0; i < n; i++)
cin >> arr[i].first >> arr[i].second;
sort(arr, arr + n);
for (int i = 0; i < n; i++) {
pfx[i + 1] = pfx[i] + arr[i].second;
pre_min = min(pre_min, pfx[i] - arr[i].first);
ans = max(ans, pfx[i + 1] - arr[i].first - pre_min);
}
cout << ans << '\n';
}
