#include <cmath>
#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
using namespace std;
using ll = long long;
ll mod = 100000000000007;
ll modpow(ll a, ll b) {
ll result = 1;
a %= mod;
while (b > 0) {
if (b % 2 == 1)
result = (result * a) % mod;
a = (a * a) % mod;
b /= 2;
}
return result;
}
ll solve(ll n, vector<pair<ll, ll>> arr) {
vector<ll> pre(n + 1);
for (ll i = 0; i < n; ++i) {
pre[i + 1] = pre[i] + arr[i].second;
}
ll ans = 0;
for (ll i = 0; i < n; ++i) {
ll mx = arr[i].first;
ll mn = arr[i].first;
for (ll j = i; j < n; ++j) {
mx = max(mx, arr[j].first);
mn = min(mn, arr[j].first);
ll h = pre[j + 1] - pre[i];
ans = max(ans, h - (mx - mn));
}
}
return ans;
}
int main() {
ll n;
cin >> n;
vector<pair<ll, ll>> vec(n);
for (int i = 0; i < n; i++) {
ll k, m;
cin >> k >> m;
vec[i] = {k, m};
}
sort(vec.begin(), vec.end());
ll ans = solve(n, vec);
cout << ans << endl;
return 0;
}
