#include<bits/stdc++.h>
#define int long long
using namespace std;
signed main(){
int n;
cin >> n;
vector<pair<int, int>> a(n); // {size, value}
for(int i = 0; i < n; ++i){
cin >> a[i].first >> a[i].second;
}
sort(a.begin(), a.end());
vector<int> prefix(n + 1);
for(int i = 0; i < n; ++i){
prefix[i + 1] = prefix[i] + a[i].second;
}
int ans = LLONG_MIN;
int prefix_min = LLONG_MAX;
for(int r = 0; r < n; ++r){
int size_r = a[r].first;
prefix_min = min(prefix_min, prefix[r] - a[r].first);
ans = max(ans, (prefix[r + 1] - a[r].first) - prefix_min);
}
cout << ans << '\n';
}
