#include <bits/stdc++.h>
#define sz(x) (int)x.size()
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define int long long
using namespace std;
using ll = long long;
using ull = unsigned long long;
using ld = long double;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
const int mod = 1e9 + 7;
const int LOG = 20;
const int maxn = 1e5 + 5;
const double eps = 1e-9;
int32_t main() {
int n;
cin >> n;
vector<pii> v(n+1);
for(int i=1; i<=n; i++) cin >> v[i].first >> v[i].second;
sort(1+all(v));
ll ans = 0;
for(int i=1; i<=n; i++) {
ll total = 0;
for(int j=i; j>=1; j--) {
total += v[j].second;
ans = max(ans, total - (v[i].first - v[j].first));
}
}
cout << ans << '\n';
return 0;
}
