#include <bits/stdc++.h>
#define f first
#define s second
#define ii pair<int, int>
#define iii pair<ii, int>
#define ll long long
#define pb push_back
#define save_time ios_base::sync_with_stdio(false); cin.tie(NULL);
const int inf = 1e9 + 7;
using namespace std;
int main() {
save_time;
int n;
cin >> n;
vector<pair<ll, ll>> v(n);
for (auto &i : v) cin >> i.f >> i.s;
sort(v.begin(), v.end());
vector<ll> pre(n + 1, -inf);
for (int i = 0; i < n; i++) pre[i + 1] = pre[i] + v[i].s;
ll mn = LLONG_MAX, mx = LLONG_MIN;
for (int i = 0; i < n; i++) {
mn = min(mn, pre[i] - v[i].f);
mx = max(mx, pre[i + 1] - v[i].f - mn);
}
cout << mx;
}
