#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<ll, ll> P;
#define DUMP(x) cout << #x << " = " << (x) << endl;
#define FOR(i, m, n) for (ll i = m; i < n; i++)
#define IFOR(i, m, n) for (ll i = n - 1; i >= m; i--)
#define REP(i, n) FOR(i, 0, n)
#define IREP(i, n) IFOR(i, 0, n)
#define FOREACH(x, a) for (auto&(x) : (a))
#define ALL(v) (v).begin(), (v).end()
#define SZ(x) ll(x.size())

int main() {
  ll n;
  cin >> n;
  vector<ll> a(2 * n);
  ll sum = 0;
  REP(i, 2 * n) {
    cin >> a[i];
    sum += a[i];
  }
  vector<ll> l(n + 1, 0), r(n + 1, 0);
  REP(i, n) {
    l[i + 1] = l[i] + a[2 * i];
    r[i + 1] = r[i] + a[2 * n - 1 - 2 * i];
  }
  ll ans = -1e18;
  REP(i, n + 1) {
    ll t = 2 * (l[i] + r[n - i]) - sum;
    ans = max(ans, t);
  }
  cout << ans << endl;
}