#include <bits/stdc++.h>
using namespace std;
typedef pair <long long, int> PLLI;
typedef long long LL;
constexpr int NMAX = 5e5 + 5;
constexpr LL INF = 1LL * 1e18;
int N;
PLLI A[NMAX];
LL sp[NMAX];
void Read () {
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
cin >> N;
for (int i = 1; i <= N; ++ i )
cin >> A[i].first >> A[i].second;
sort(A+1, A+N+1);
}
void Solve () {
for (int i = 1; i <= N; ++ i )
sp[i] = sp[i-1] + 1LL * A[i].second;
set <LL> S;
LL ans = -INF;
for (int i = 1; i <= N; ++ i ) {
S.insert(sp[i-1] - A[i].first);
LL value = *(S.begin());
ans = max(ans, sp[i] - A[i].first - value);
}
cout << ans << '\n';
}
int main () {
Read();
Solve();
return 0;
}
