#include <bits/stdc++.h>
// solved by bekagg
#define int long long
#define ent '\n'
#define pb push_back
#define all(x) x.begin(),x.end()
#define PRaim_bek_abi ios_base::sync_with_stdio(0);cin.tie(0);
using namespace std;
const int N = 5e5+5;
const int MOD = 1e9+7;
int n , pref[N];
vector<pair<int , int> > v;
void arkanefury228(){
cin >> n;
int ans = 0;
for (int i = 1; i <= n; i++){
int a , b;
cin >> a >> b;
ans = max(ans , b);
v.pb({a , b});
}
sort(all(v));
multiset<int>s;
for (int i = 1; i <= n; i++){
pref[i] = pref[i - 1] + v[i - 1].second;
s.insert(pref[i] - (v[i - 1].first - v[0].first));
}
int sum = 0;
ans = max(ans , *s.rbegin());
for (int i = 1; i < n; i++){
s.erase(s.find(pref[i] - (v[i - 1].first - v[0].first)));
sum += (v[i].first - v[i - 1].first);
sum -= v[i - 1].second;
ans = max(ans , *s.rbegin() + sum);
}
cout << ans;
}
signed main(){
PRaim_bek_abi
int t=1;
//cin>>t;
for (int respagold = 1; respagold <= t; respagold++) arkanefury228();
}
