#include <bits/stdc++.h>
#define all(v) v.begin(), v.end()
#define chmax(x, v) x = max(x, v)
#define chmin(x, v) x = min(x, v)
#define sz(v) (int)v.size()
#define pb push_back
#define int long long
using namespace std;
struct Oeuvre {
int val, taille;
bool operator < (const Oeuvre &autre) const {
if (taille != autre.taille)
return taille > autre.taille;
return val < autre.val;
}
};
signed main(){
ios::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
int nOeuvres;
cin >> nOeuvres;
vector<Oeuvre> oeuvres(nOeuvres);
for (Oeuvre& oeuvre : oeuvres)
cin >> oeuvre.taille >> oeuvre.val;
sort(all(oeuvres));
vector<int> cum(nOeuvres, 0);
for (int ind = 1; ind < nOeuvres; ++ind)
cum[ind] = cum[ind - 1] + oeuvres[ind].val;
int maxi = 0, mini = 1e15;
for (int fin = 0; fin < nOeuvres; ++fin){
int S = cum[fin] + oeuvres[fin].taille;
chmin(mini, S - oeuvres[fin].val);
chmax(maxi, S - mini);
// cout << maxi << " " << S << " " << mini << endl;
}
cout << maxi << endl;
return 0;
}
