#include <bits/stdc++.h>
#define ll long long
using namespace std;
const ll N = 1e6, mod = 1e9 + 7, inf = 1e18;
int main() {
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
int n;
cin >> n;
vector<ll> a(n);
vector<ll> b(n);
vector<pair<ll, ll>> p(n);
for (int i = 0; i < n; i++) {
cin >> a[i] >> b[i];
p[i] = {a[i], b[i]};
}
vector<ll> prefsum(n + 1, 0);
sort(p.begin(), p.end());
for (int i = 0; i < n; i++) {
prefsum[i + 1] = prefsum[i] + p[i].second;
}
vector<ll> v;
vector<ll> prefm(n, 0);
ll mxd = -1;
ll e = prefsum[n] - (p[n - 1].first - p[0].first);
for (int i = 0; i < n; i++) {
v.push_back(p[i].first - p[0].first - prefsum[i]);
mxd = max(mxd, v.back());
prefm[i] = mxd;
}
ll ans = e;
for (int i = n - 1; i >= 1; i--) {
ll d = p[n - 1].first - p[i].first - (prefsum[n] - prefsum[i + 1]);
ans = max(ans, p[i].second);
ans = max(ans, e + prefm[i - 1] + d);
}
cout << ans << '\n';
}
