#include <iostream>
#include <algorithm>
#include <vector>
#include <unordered_map>
#include <chrono>
using namespace std;
typedef long long ll;
signed main() {
cin.tie(0) -> sync_with_stdio(0);
ll n;
cin >> n;
// {size, val}
vector<pair<ll, ll>> nums(n);
for (auto &p: nums) {
cin >> p.first >> p.second;
}
sort(nums.rbegin(), nums.rend());
ll res = 0;
for (ll i = 0; i<n; ++i) {
ll val = 0;
ll mn = nums[i].first;
for (ll j = i; j<n; ++j) {
mn = min(mn, nums[j].first);
val += nums[j].second;
res = max(res, val - nums[i].first + mn);
}
}
cout << res << '\n';
}
