#include <bits/stdc++.h>
using namespace std;

int main() {
    int N; cin >> N;
    vector<int64_t> A(N), B(N);
    for(int i = 0; i < N; ++i) {
        int a, b; cin >> a >> b;
        A[i] = a - b;
        B[i] = b - a;
    }
    for(int i = 0; i < N - 1; ++i) A[i + 1] += A[i];
    for(int i = N - 1; i >= 1; --i) B[i - 1] += B[i];
    int64_t ans = max(A[N - 1], B[0]);
    for(int i = 0; i < N - 1; ++i) ans = max(ans, A[i] + B[i + 1]);
    cout << ans << '\n';
    return 0;
}