#include <bits/stdc++.h>
#define int long long
using namespace std;
typedef pair<int,int> p;
#define f first
#define s second
signed main(){
int n;
cin >> n;
vector<p> artworks(n);
for (int i = 0; i < n; i++){
cin >> artworks[i].f >> artworks[i].s; // size, value
}
sort(artworks.begin(), artworks.end()); // sort by size
int ans = 0;
int prefix_sum = 0;
int min_prefix_minus_first = 0; // minimum of (prefix_sum - first_size)
for (int i = 0; i < n; i++){
int size = artworks[i].f;
int value = artworks[i].s;
prefix_sum += value;
// Current answer if we end at position i
// S - (Amax - Amin) = prefix_sum - (current_size - min_size_in_range)
// We want to maximize: prefix_sum - current_size + min_size_in_range
// This equals: prefix_sum - current_size - min(prefix_sum_at_start - size_at_start)
ans = max(ans, prefix_sum - size - min_prefix_minus_first);
// Update minimum for next iteration
min_prefix_minus_first = min(min_prefix_minus_first, prefix_sum - size);
}
cout << ans << endl;
return 0;
}
