#include <bits/stdc++.h>

using namespace std;
using ll = long long;
using VI = vector<int>;
using VL = vector<int>;
using PII = std::pair<int, int>;
using PLL = std::pair<ll, ll>;

#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define rep2(i, s, n) for (int i = (s); i < (int)(n); i++)
#define allpt(v) (v).begin(), (v).end()


const int mod = 1e9 + 7;
const string wsp = " ";
const string tb = "\t";
const string rt = "\n";

template <typename T>
void show1dvec(vector<T> v)
{
    int n = v.size() - 1;
    rep(i, n) cout << v[i] << wsp;
    cout << v[n] << rt;
    return;
}

int main()
{

#ifdef DEBUG
    cout << "DEBUG MODE" << endl;
    ifstream in("input.txt"); //for debug
    cin.rdbuf(in.rdbuf());    //for debug
#endif

    ll n, sum;
    cin >> n;
    VL v(2 * n), s(n + 1);

    rep(i, 2 * n) cin >> v[i];
    sum = 0;
    rep(i, n)
    {
        sum += v[2 * i] - v[2 * i + 1];
    }
    s[0] = sum;
    rep(i, n)
    {
        s[i + 1] = s[i] + 2 * (v[2 * n - 1 - 2 * i] - v[2 * n - 2 - 2 * i]);
    }
    cout << *max_element(allpt(s)) << rt;

    return 0;
}