#include<bits/stdc++.h>
using namespace std;
using ll = long long;
typedef pair<ll, ll> pii;
int main() {
ios_base::sync_with_stdio(false);
cin.tie(NULL);
int n;
cin >> n;
vector <pii> v(n);
for (pii &p : v) cin >> p.first >> p.second;
sort(v.begin(), v.end());
// Make prefix sum
for (int i = 1; i < n; i++) v[i].second += v[i - 1].second;
ll output = 0;
int i, j = 0;
for (i = 0; i < n; i++)
{
// When i changes, you could increase j to i
if (v[i].second - (i != 0 ? v[i - 1].second : 0) > v[i].second - (j != 0 ? v[j - 1].second : 0) - v[i].first + v[j].first) j = i;
output = max(output, v[i].second - (j != 0 ? v[j - 1].second : 0) - v[i].first + v[j].first);
}
cout << output << "\n";
}
/*
Will be continous segments.
....a....b....
then if c > b -> d >=a
....ddd...c
*/
