#include <bits/stdc++.h>
using namespace std;
#define int long long
#define ii pair<int,int>
#define fi first
#define sc second
#define all(x) (x).begin(),(x).end()
const int N = 500005;
ii a[N];
int sum[N], mi[N];
signed main() {
// freopen("in" , "r", stdin );
cin.tie(0)->sync_with_stdio(0);
int n; cin >> n;
for (int i = 1; i <= n; i++) {
cin >> a[i].fi >> a[i].sc;
}
sort(a + 1, a + n + 1);
for (int i = 1; i <= n; i++) {
sum[i] = sum[i - 1] + a[i].sc;
}
for (int i = 0; i < n; i++) {
mi[i] = sum[i] - a[i + 1].fi;
if (i) mi[i] = min(mi[i], mi[i - 1]);
}
int ans = LLONG_MIN;
for (int i = 1; i <= n; i++) {
ans = max(ans, sum[i] - a[i].fi - mi[i - 1]);
}
cout << ans << '\n';
}
