/*
written by sim_ple
*/
#include <bits/stdc++.h>
using namespace std;
#define int long long
#define N 500005
#define itn int
#define all(x) x.begin() , x.end()
void solve(){
int n;
cin >> n;
vector<pair<int , int>> v(n + 1);
for(int i = 1; i <= n; i++){
cin >> v[i].first >> v[i].second;
}
sort(all(v));
int pref[n + 1];
memset(pref , 0 , sizeof(pref));
pref[1] = v[1].second;
for(int i = 2; i <= n; i++){
pref[i] = pref[i - 1] + v[i].second;
}
int ans = 0 , mn = -v[1].first;
for(int i = 1; i <= n; i++){
int co = pref[i] - v[i].first - mn;
ans = max(ans , co);
mn = min(mn , pref[i] - v[i].first);
}
cout << ans << endl;
}
int32_t main() {
ios::sync_with_stdio(false);cin.tie(nullptr);
int t = 1;
//cin >> t;
while(t--) solve();
}
