#include <bits/stdc++.h>
#define int long long
using namespace std;
int n;
pair<int, int> a[501010];
multiset<pair<int, int> > now;
int ans = -8010101010101010101;
int32_t main()
{
cin >> n;
for (int i = 1; i <= n; i++)
cin >> a[i].first >> a[i].second;
sort(a + 1, a + 1 + n, [](pair<int, int> q, pair<int, int> w) {
return q.first < w.first;
});
int sum = 0;
for (int i = 1; i <= n; i++) {
sum += a[i].second;
now.insert({-(sum - a[i].first), i});
}
int er = 0;
for (int i = 1; i <= n; i++) {
while (true) {
// cout << now.size() << " " << i << " << " << endl;
auto f = *now.begin();
now.erase(now.begin());
// cout << f.first << " " << f.second << " " << i << " !!!" << endl;
if (f.second < i)continue;
ans = max(ans, ((-f.first) - er) + a[i].first);
now.insert(f);
break;
}
er += a[i].second;
}
cout << ans;
}
/**
15
1543361732 260774320
2089759661 257198921
1555665663 389548466
4133306295 296394520
2596448427 301103944
1701413087 274491541
2347488426 912791996
2133012079 444074242
2659886224 656957044
1345396764 259870638
2671164286 233246973
2791812672 585862344
2996614635 91065315
971304780 488995617
1523452673 988137562
6
4 1
1 5
10 3
9 1
4 2
5 3
3
2 3
11 2
4 5
*/
