#include<bits/stdc++.h>

#define rep(i, n) for (int i = 0; i < (int) n; i++)

using ll = long long;
using namespace std;

const long long INF = 1ll << 60;

void chmax(ll &x, ll y) {
    x = max(x, y);
}

int main() {
    ll n;
    cin >> n;
    deque<ll> c;
    rep(i, n) {
        ll ci;
        cin >> ci;
        c.push_back(ci);
    };
    
    ll ans = -INF;
    // big big
    {
        deque<ll> ci = c;
        vector<ll> score(2, 0);
        rep(i, n) {
            score[i % 2] += ci.front();
            ci.pop_front();
        }
        chmax(ans, abs(score[0]) - abs(score[1]));
    }
    // big small
    {
        deque<ll> ci = c;
        vector<ll> score(2, 0);
        rep(i, n) {
            if (i % 2) {
                score[i % 2] += ci.front();
                ci.pop_front();
            } else {
                score[i % 2] += ci.back();
                ci.pop_back();
            }
        }
        chmax(ans, abs(score[0]) - abs(score[1]));
    }
    // small big
    {
        deque<ll> ci = c;
        vector<ll> score(2, 0);
        rep(i, n) {
            if (i % 2) {
                score[i % 2] += ci.back();
                ci.back();
            } else {
                score[i % 2] += ci.front();
                ci.pop_front();
            }
        }
        chmax(ans, abs(score[0]) - abs(score[1]));
    }
    //  small small
    {
        deque<ll> ci = c;
        vector<ll> score(2, 0);
        rep(i, n) {
            score[i % 2] += ci.back();
            ci.pop_back();
        }
        chmax(ans, abs(score[0]) - abs(score[1]));
    }
    cout << ans << endl;
}