#pragma GCC optimize("Ofast")
#include <bits/stdc++.h>
#define ll long long
#define F first
#define S second
#define pb push_back
#define endl '\n'
#define all(v) (v).begin(),(v).end()
using namespace std;
const int N = 500005;
const int INF = 1000000000;
const ll INFLL = 1LL * INF * INF;
pair <ll, int> a[N];
ll p[N];
int main() {
ios_base :: sync_with_stdio(0);
cin.tie(0); cout.tie(0);
int n;
cin >> n;
for (int i = 1; i <= n; i++) {
cin >> a[i].F >> a[i].S;
}
sort(a + 1, a + n + 1);
for (int i = 1; i <= n; i++) {
p[i] = p[i - 1] + a[i].S;
}
ll res = -INF;
for (int i = 1; i <= n; i++) {
for (int j = i; j <= n; j++) {
res = max(res, (p[j] - p[i - 1]) - (a[j].F - a[i].F));
}
}
cout << res << endl;
return 0;
}
