#pragma region Macros
#include <bits/stdc++.h>
using namespace std;
template <class T> inline bool chmax(T &a, T b) {
    if(a < b) {
        a = b;
        return 1;
    }
    return 0;
}
template <class T> inline bool chmin(T &a, T b) {
    if(a > b) {
        a = b;
        return 1;
    }
    return 0;
}
#ifdef DEBUG
template <class T, class U>
ostream &operator<<(ostream &os, const pair<T, U> &p) {
    os << '(' << p.first << ',' << p.second << ')';
    return os;
}
template <class T> ostream &operator<<(ostream &os, const vector<T> &v) {
    os << '{';
    for(int i = 0; i < (int)v.size(); i++) {
        if(i) { os << ','; }
        os << v[i];
    }
    os << '}';
    return os;
}
void debugg() { cerr << endl; }
template <class T, class... Args>
void debugg(const T &x, const Args &... args) {
    cerr << " " << x;
    debugg(args...);
}
#define debug(...)                                                             \
    cerr << __LINE__ << " [" << #__VA_ARGS__ << "]: ", debugg(__VA_ARGS__)
#define dump(x) cerr << __LINE__ << " " << #x << " = " << (x) << endl
#else
#define debug(...) (void(0))
#define dump(x) (void(0))
#endif

struct Setup {
    Setup() {
        cin.tie(0);
        ios::sync_with_stdio(false);
        cout << fixed << setprecision(15);
    }
} __Setup;

using ll = long long;
#define ALL(v) (v).begin(), (v).end()
#define RALL(v) (v).rbegin(), (v).rend()
#define FOR(i, a, b) for(int i = (a); i < int(b); i++)
#define REP(i, n) FOR(i, 0, n)
const int INF = 1 << 30;
const ll LLINF = 1LL << 60;
constexpr int MOD = 1000000007;
const int dx[4] = {1, 0, -1, 0};
const int dy[4] = {0, 1, 0, -1};

void Case(int i) { cout << "Case #" << i << ": "; }
int popcount(int x) { return __builtin_popcount(x); }
ll popcount(ll x) { return __builtin_popcountll(x); }
#pragma endregion Macros

int main() {
    int N;
    cin >> N;
    vector<int> p(N);
    REP(i, N) cin >> p[i], p[i]--;

    ll ans = -LLINF;
    int mid = N/2;
    FOR(d, -3, 4) {
        int m = clamp(mid+d, 0, N-1);
        set<int> se;
        REP(i, N) se.insert(i);
        debug(m);
        ll sum = 0;
        for(int i = N-1; i >= 0; i--) {
            auto it = se.lower_bound(p[i]+1);
            if(it != se.end()) {
                sum += i+1;
                se.erase(it);
            } else {
                if(i >= m) {
                    auto it2 = se.lower_bound(p[i]);
                    if(it2 != se.end()) {
                        se.erase(it2);
                    } else {
                        sum -= i+1;
                        se.erase(se.begin());
                    }
                } else {
                    se.erase(se.begin());
                    sum -= i+1;
                }
            }
        }
        chmax(ans, sum);
    }

    cout << ans << endl;
}