#include <bits/stdc++.h>
using namespace std;
#define int long long
bool cmp(pair<int, int> a, pair<int, int> b) {
if(a.first == b.first)
return a.second < b.second;
return a.first < b.first;
}
void Solve() {
int n;
cin >> n;
vector<pair<int, int> > a(n + 1); //size, value;
for(int i = 1; i <= n; i++) {
cin >> a[i].first >> a[i].second;
}
if(n == 1)
{
cout << a[1].second << "\n";
return;
}
sort(a.begin(), a.end(), cmp);
int values[n + 1]; //values with respect to position 1
values[1] = a[1].second;
for(int i = 2; i <= n; i++) {
values[i] = values[i - 1] + a[i].second - (a[i].first - a[i - 1].first);
}
for(int i = n - 1; i > 0; i--) {
values[i] = max(values[i], values[i + 1]);
}
int diff = 0, ans = 0;
for(int i = 1; i < n; i++) {
ans = max(ans, values[i] - diff);
diff += a[i].second;
diff -= (a[i + 1].first - a[i].first);
}
cout << ans << "\n";
}
int32_t main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
Solve();
return 0;
}
