#include<bits/stdc++.h>
#include<ext/pb_ds/assoc_container.hpp>
#include<ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
using namespace std;
using ll = long long;
#define all(x) x.begin(), x.end()
#define oset tree<ll, null_type, less<ll>, rb_tree_tag, tree_order_statistics_node_update>
int main(){
ios::sync_with_stdio(false);
cin.tie(0);
//ifstream cin("inputf.txt");
//ofstream cout("outputfv.txt");
ll n; cin >> n;
vector<pair<ll, ll>> a(n);
vector<ll> pref(n);
for(int i = 0; i < n; i++){
cin >> a[i].first >> a[i].second;
}
sort(all(a));
for(int i = 0; i < n; i++){
pref[i] = (i > 0 ? pref[i-1] : 0) + a[i].second;
}
ll ans = 0;
ll mn = -a[0].first;
for(int i = 0; i < n; i++){
ans = max(ans, pref[i] - a[i].first - mn);
mn = min(mn, pref[i] - a[i+1].first);
}
cout << ans << '\n';
}
