#include <algorithm>
#include <array>
#include <bitset>
#include <cassert>
#include <chrono>
#include <cmath>
#include <cstring>
#include <functional>
#include <iomanip>
#include <iostream>
#include <limits>
#include <map>
#include <numeric>
#include <queue>
#include <random>
#include <set>
#include <vector>
using namespace std;
int main() {
int N;
cin >> N;
vector<array<int64_t, 2>> A(N);
for (auto &[x, y] : A)
cin >> x >> y;
sort(A.begin(), A.end());
priority_queue<int64_t> Q;
Q.push((A[1][0] - A[0][0]) - A[0][1]);
int64_t answer = A[0][1];
int64_t prefix = A[0][1];
int64_t remove_prefix = (A[1][0] - A[0][0]) - A[0][1];
for (int i = 1; i < N; i++) {
prefix += A[i][1];
prefix -= abs(A[i][0] - A[i - 1][0]);
answer = max<int64_t>(answer, prefix);
answer = max<int64_t>(answer, prefix + Q.top());
remove_prefix -= A[i][1];
remove_prefix += (A[i][1] - A[i - 1][1]);
Q.push(remove_prefix);
}
cout << answer;
}
