#include <bits/stdc++.h>
using namespace std;
const long long INF = 1e18;
int main() {
int N;
cin >> N;
vector<long long> A(N), B(N);
for (int i = 0; i < N; i++) {
cin >> A[i] >> B[i];
}
vector<int> order(N);
iota(order.begin(), order.end(), 0);
sort(order.begin(), order.end(), [&](int i, int j) {
return A[i] < A[j];
});
vector<long long> C;
for (int i = 0; i < N; i++) {
C.push_back(B[order[i]]);
if (i < N - 1) {
C.push_back(A[order[i]] - A[order[i + 1]]);
}
}
long long Min[2] = {0, INF}, sum = 0, ans = 0;
for (int i = 0; i < 2 * N - 1; i++) {
sum += C[i];
ans = max(ans, sum - Min[i % 2]);
Min[(i + 1) % 2] = min(Min[(i + 1) % 2], sum);
}
cout << ans << "\n";
}
