#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const int N = 5e5 + 5, inf = 2e9;
int n;
pair <ll, ll> p[N];
int main() {
ios_base::sync_with_stdio(0); cin.tie(0);
//freopen("test.inp", "r", stdin);
// freopen(".OUT", "w", stdout);
cin >> n;
for (int i=1;i<=n;++i) cin >> p[i].first >> p[i].second;
sort(p + 1, p + n + 1);
for (int i=1;i<=n;++i)
p[i].second += p[i - 1].second;
ll MIN = -p[1].first, ans = -9e18;
for (int i = 1; i <= n; ++i) {
ans = max(ans, p[i].second - p[i].first - MIN);
MIN = min(MIN, p[i].second - p[i + 1].first);
}
cout << ans;
}
