#include <bits/stdc++.h>
using namespace std;
#define int long long
#define all(x) (x).begin(), (x).end()
#define F first
#define S second
#define nn '\n'
#define pb push_back
signed main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
int n;
cin >> n;
vector<pair<int,int>> a(n);
for (int i = 0; i < n; i++) cin >> a[i].first >> a[i].second;
sort(all(a));
int mx = -1;
for (int i = 0; i < n; i++) {
int sum = 0;
for (int j = i; j < n; j++) {
sum += a[j].S;
mx = max(mx , sum - (a[j].F - a[i].F));
}
}
cout << mx;
}
