#include <bits/stdc++.h>
using namespace std;
const int N = 5e5 + 1 ;
#define ll long long
int main()
{ios_base::sync_with_stdio(false);cin.tie(0);
int n ;
cin >> n ;
vector<pair<ll , ll > > v (n);
for(auto &it : v)
cin >> it.first >> it.second ;
sort(v.begin() , v.end());
ll mx = v[n - 1].second , sum1 = 0 , sum2 = v[n - 1].second;
ll past = v[n - 1].first ;
for(int i = n - 2 ; i >= 0 ; i --){
sum1 += past - v[i].first ;
if(sum1 > sum2)
sum1 = sum2 = 0 ;
sum2 += v[i].second ;
mx = max(mx , sum2 - sum1);
past = v[i].first ;
}
cout << mx ;
return 0;
}
