#include <bits/stdc++.h>
using namespace std;
#define int long long
signed main() {
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cout.tie(NULL);
int n;
cin >> n;
vector<pair<int, int>> v(n + 1);
for(int i = 1; i <= n; i++){
cin >> v[i].first >> v[i].second;
}
sort(v.begin(), v.end());
int p[n + 1];
p[0] = 0;
for(int i = 1; i <= n; i++){
p[i] = p[i - 1] + v[i].second;
}
int ans = -1;
for(int i = 1; i < n; i++){
for(int j = i + 1; j < n; j++){
ans = max(ans, p[j] - p[i - 1] - (v[j].first - v[i].first));
}
}
cout << ans;
return 0;
}
