#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int maxn = 1e5 + 10;;
ll n, pref[maxn];
vector<pair<ll, ll>> v;
ll bit[maxn];
int main()
{
ios::sync_with_stdio(false), cin.tie(nullptr);
cin >> n;
for(int i = 0; i < n; i++)
{
ll a, b;
cin >> a >> b;
v.push_back({a, b});
}
sort(v.begin(), v.end());
for(int i = 0; i < n; i++)
{
if(!i) pref[i] = v[i].second;
else
{
pref[i] = pref[i - 1] + v[i].second;
}
}
ll ans = 0;
for(int i = 0; i < n - 1; i++)
{
ll sum = v[i].second;
for(int j = i + 1; j < n; j++)
{
sum += v[j].second;
ans = max(ans, sum - (v[j].first- v[i].first));
}
}
cout << ans << "\n";
}
