#include <bits/stdc++.h>
using namespace std;
#define int long long
#define fori for(int i=0;i<n;i++)
int32_t main(){
ios::sync_with_stdio(false);
cin.tie(nullptr);
int n;
cin >> n;
vector<pair<int,int>> art(n);
fori cin >> art[i].first >> art[i].second;
sort(art.begin(), art.end());
int sum = 0, l = 0, res = LLONG_MIN;
for(int r = 0; r < n; r++){
sum += art[r].second;
while(l <= r && (art[r].first - art[l].first) > sum){
sum -= art[l].second;
l++;
}
int Amax = art[r].first;
int Amin = art[l].first;
res = max(res, sum - (Amax - Amin));
}
cout << res;
}
