#include <bits/stdc++.h>
using namespace std;
using ll = long long;
int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
cout.tie(nullptr);
ll n; cin >> n;
vector<pair<ll, ll>> a(n + 1); a[0].first = -99999;
for (int i = 1; i <= n; i++) cin >> a[i].first >> a[i].second;
sort(a.begin(), a.end());
vector<ll> p(n + 1); p[0] = 0;
for (ll i = 1; i <= n; i++) p[i] = a[i].second + p[i - 1];
ll ans = 0;
for (ll i = 1; i <= n; i++)
for (ll j = i; j <= n; j++)
ans = max(ans, p[j] - a[j].first - p[i - 1] + a[i].first);
cout << ans;
}
