#include <iostream>
#include <vector>
#include <algorithm>
#include <unordered_set>
#include <cstring>
#include <array>
#include <cmath>
#include <stack>
#include <queue>
#include <map>
#include <set>
#define INF 1e18
using namespace std;
typedef long long ll;
const ll MOD = 1000000007;
const ll MAXN = 1005;
void solve()
{
int n; cin >> n;
vector<pair<ll, ll>>v(n);
for (int i = 0; i < n; i++)cin >> v[i].first >> v[i].second;
sort(v.begin(), v.end());
vector<ll>p(n + 1);
for (int i = 0; i < n; i++)p[i + 1] = p[i] + v[i].second;
ll ans = -INF;
for (int i = 0; i < n; i++) {
for (int j = i; j < n; j++) {
ll mx = v[j].first; ll mn = v[i].first;
ll sum = p[j + 1] - p[i];
ans = max(ans, sum - (mx - mn));
}
}
cout << ans << "\n";
}
int main()
{
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
int t = 1;// cin >> t;
while (t--) solve();
return 0;
}
