#ifdef LOCAL
#include ".debug.hpp"
#else
#define debug(...) 42
#endif
#pragma GCC optimize("Ofast")
#include <bits/stdc++.h>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;
using namespace std;
using ordered_set = tree<int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update>;
signed main() {
#ifndef VOID
cin.tie(nullptr)->sync_with_stdio(false);
#endif
int N; cin >> N;
vector<array<int64_t, 2>> A(N + 1); for (int i = 1; i <= N; i++) cin >> A[i][0] >> A[i][1];
sort(A.begin(), A.end());
vector<int64_t> suff(N + 5), pref(N + 5);
int64_t ans = 0;
for (int i = N; i >= 1; i--) suff[i] = suff[i + 1] + A[i][1], ans = max(ans, A[i][1]);
for (int i = 1; i <= N; i++) pref[i] = pref[i - 1] + A[i][1];
priority_queue<array<int64_t, 2>> pq;
for (int i = 1; i <= N; i++) {
if (!pq.empty()) {
int j = pq.top()[1];
int64_t sum = pref[i] - pref[j - 1];
ans = max(ans, sum - A[i][0] + A[j][0]);
}
pq.push({suff[i] + A[i][0], i});
}
cout << ans;
return 0;
}
