#include <algorithm>
#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define all(x) (x).begin(), (x).end()
#define ll long long
#define INF 1000000000000000000

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);

    int N;
    cin >> N;
    vector<ll> left(N + 1, 0), right(N + 1, 0);
    ll sum = 0;
    rep(i, N) {
        ll a, b;
        cin >> a >> b;
        sum += (a + b);
        left[i + 1] = a;
        right[N - i] = b;
    }

    rep(i, N) {
        left[i + 1] += left[i];
        right[i + 1] += right[i];
    }

    ll homura = 0, tenpura = 0;

    rep(i, N) { homura = max(homura, left[i] + right[N - i]); }

    cout << 2 * homura - sum << endl;
}