#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (n); i++)
#define per(i, n) for (int i = (n)-1; i >= 0; i--)
#define rep2(i, l, r) for (int i = (l); i < (r); i++)
#define per2(i, l, r) for (int i = (r)-1; i >= (l); i--)
#define each(e, v) for (auto &e : v)
#define MM << " " <<
#define pb push_back
#define eb emplace_back
#define all(x) begin(x), end(x)
#define rall(x) rbegin(x), rend(x)
#define sz(x) (int)x.size()
using ll = long long;
using pii = pair<int, int>;
using pil = pair<int, ll>;
using pli = pair<ll, int>;
using pll = pair<ll, ll>;

template <typename T>
using minheap = priority_queue<T, vector<T>, greater<T>>;

template <typename T>
using maxheap = priority_queue<T>;

template <typename T>
bool chmax(T &x, const T &y) {
    return (x < y) ? (x = y, true) : false;
}

template <typename T>
bool chmin(T &x, const T &y) {
    return (x > y) ? (x = y, true) : false;
}

template <typename T>
int flg(T x, int i) {
    return (x >> i) & 1;
}

int popcount(int x) { return __builtin_popcount(x); }
int popcount(ll x) { return __builtin_popcountll(x); }
int topbit(int x) { return (x == 0 ? -1 : 31 - __builtin_clz(x)); }
int topbit(ll x) { return (x == 0 ? -1 : 63 - __builtin_clzll(x)); }
int botbit(int x) { return (x == 0 ? -1 : __builtin_ctz(x)); }
int botbit(ll x) { return (x == 0 ? -1 : __builtin_ctzll(x)); }

template <typename T>
void print(const vector<T> &v, T x = 0) {
    int n = v.size();
    for (int i = 0; i < n; i++) cout << v[i] + x << (i == n - 1 ? '\n' : ' ');
    if (v.empty()) cout << '\n';
}

template <typename T>
void printn(const vector<T> &v, T x = 0) {
    int n = v.size();
    for (int i = 0; i < n; i++) cout << v[i] + x << '\n';
}

template <typename T>
int lb(const vector<T> &v, T x) {
    return lower_bound(begin(v), end(v), x) - begin(v);
}

template <typename T>
int ub(const vector<T> &v, T x) {
    return upper_bound(begin(v), end(v), x) - begin(v);
}

template <typename T>
void rearrange(vector<T> &v) {
    sort(begin(v), end(v));
    v.erase(unique(begin(v), end(v)), end(v));
}

template <typename T>
vector<int> id_sort(const vector<T> &v, bool greater = false) {
    int n = v.size();
    vector<int> ret(n);
    iota(begin(ret), end(ret), 0);
    sort(begin(ret), end(ret), [&](int i, int j) { return greater ? v[i] > v[j] : v[i] < v[j]; });
    return ret;
}

template <typename T>
void reorder(vector<T> &a, const vector<int> &ord) {
    int n = a.size();
    vector<T> b(n);
    for (int i = 0; i < n; i++) b[i] = a[ord[i]];
    swap(a, b);
}

template <typename T>
T floor(T x, T y) {
    assert(y != 0);
    if (y < 0) x = -x, y = -y;
    return (x >= 0 ? x / y : (x - y + 1) / y);
}

template <typename T>
T ceil(T x, T y) {
    assert(y != 0);
    if (y < 0) x = -x, y = -y;
    return (x >= 0 ? (x + y - 1) / y : x / y);
}

template <typename S, typename T>
pair<S, T> operator+(const pair<S, T> &p, const pair<S, T> &q) {
    return make_pair(p.first + q.first, p.second + q.second);
}

template <typename S, typename T>
pair<S, T> operator-(const pair<S, T> &p, const pair<S, T> &q) {
    return make_pair(p.first - q.first, p.second - q.second);
}

template <typename S, typename T>
istream &operator>>(istream &is, pair<S, T> &p) {
    S a;
    T b;
    is >> a >> b;
    p = make_pair(a, b);
    return is;
}

template <typename S, typename T>
ostream &operator<<(ostream &os, const pair<S, T> &p) {
    return os << p.first << ' ' << p.second;
}

struct io_setup {
    io_setup() {
        ios_base::sync_with_stdio(false);
        cin.tie(NULL);
        cout << fixed << setprecision(15);
    }
} io_setup;

const int inf = (1 << 30) - 1;
const ll INF = (1LL << 60) - 1;
// const int MOD = 1000000007;
const int MOD = 998244353;

template <typename T>
struct Splay_Tree {
    struct Node {
        Node *lch, *rch, *par;
        T x;
        int size; // 部分木のサイズ

        Node(T x) : lch(NULL), rch(NULL), par(NULL), x(x), size(1) {}

        Node() : Node(0) {}

        int state() {
            if (!this->par) return 0;
            if (this->par->lch == this) return 1;
            if (this->par->rch == this) return -1;
            return 0;
        }

        // 再帰的に子の Node のメモリを解放していく
        void rec_delete() {
            deleter(lch);
            deleter(rch);
        }

        void deleter(Node *child) {
            if (child) {
                child->rec_delete();
                delete child;
            }
        }
    };

    Node *root;

    Splay_Tree() : root(NULL) {}

    // ~Splay_Tree() {
    //     if (root) {
    //         root->rec_delete();
    //         delete root;
    //     }
    // }

    int size() { return (root ? root->size : 0); }

    void update(Node *t) {
        t->size = 1;
        if (t->lch) t->size += t->lch->size;
        if (t->rch) t->size += t->rch->size;
    }

    void rotate(Node *t) {
        Node *p = t->par, *q = p->par, *c = t->rch;
        if (p->lch == t) {
            c = t->rch, t->rch = p, p->lch = c;
        } else {
            c = t->lch, t->lch = p, p->rch = c;
        }
        if (q && q->lch == p) q->lch = t;
        if (q && q->rch == p) q->rch = t;
        t->par = q, p->par = t;
        if (c) c->par = p;
        update(p), update(t);
    }

    void splay(Node *t) {
        while (t->state() != 0) {
            if (t->par->state() == 0) {
                rotate(t);
            } else if (t->state() == t->par->state()) {
                rotate(t->par), rotate(t);
            } else {
                rotate(t), rotate(t);
            }
        }
        root = t;
    }

    // i 番目 (0-indexed) の値
    Node *get(int i) {
        if (i >= root->size) return NULL;
        Node *now = root;
        while (true) {
            int lsize = (now->lch ? now->lch->size : 0);
            if (i == lsize) break;
            if (i < lsize) {
                now = now->lch;
            } else {
                i -= lsize + 1, now = now->rch;
            }
        }
        splay(now);
        return now;
    }

    T operator[](int i) { return get(i)->x; }

    Node *make_node(const T &x) { return new Node(x); }

    // x 以上で最小のノード
    Node *lower_bound(T x) {
        Node *now = root, *ret = NULL;
        while (now) {
            if (now->x < x) {
                now = now->rch;
            } else {
                ret = now;
                now = now->lch;
            }
        }
        if (ret) splay(ret);
        return ret;
    }

    // x より大きい最小のノード
    Node *upper_bound(T x) {
        Node *now = root, *ret = NULL;
        while (now) {
            if (now->x <= x) {
                now = now->rch;
            } else {
                ret = now;
                now = now->lch;
            }
        }
        if (ret) splay(ret);
        return ret;
    }

    Node *find(T x) {
        Node *ret = lower_bound(x);
        if (!ret || ret->x != x) return NULL;
        return ret;
    }

    void insert(T x) {
        Node *c = lower_bound(x);
        if (c && c->x == x) return;
        Node *t = make_node(x);
        if (!c) {
            if (root) root->par = t;
            t->lch = root;
        } else {
            splay(c);
            if (c->lch) c->lch->par = t;
            t->lch = c->lch, t->rch = c;
            c->lch = NULL, c->par = t;
            update(c);
        }
        update(t), root = t;
    }

    void erase(T x) {
        Node *t = find(x);
        if (!t) return;
        if (t->rch) {
            t->rch->par = NULL;
            Node *c = upper_bound(x);
            c->lch = t->lch;
            if (t->lch) t->lch->par = c;
            update(c);
        } else {
            if (t->lch) t->lch->par = NULL;
            root = t->lch;
        }
        delete t;
    }

    T median() {
        assert(size() > 0);
        int k = size() / 2;
        // cout << "!" MM k << '\n';
        return get(k)->x;
    };
};

void solve() {
    int N;
    cin >> N;

    vector<int> a(N);
    rep(i, N) cin >> a[i];
    sort(all(a));

    rep(i, N) a[i] -= i;
    // print(a);

    // Splay_Tree<pii> s1;
    // rep(i, N) {
    //     s1.insert(pii(a[i], i));
    //     cout << s1.median() << '\n';
    // }

    vector<Splay_Tree<pii>> s;
    vector<pii> ps;
    rep(i, N) {
        if (empty(s)) {
            s.eb();
            s.back().insert(pii(a[i], i));
            ps.eb(i, i + 1);
        } else {
            int K = sz(s);
            if (a[i] > s[K - 1].median().first) {
                s.pb(Splay_Tree<pii>());
                s.back().insert(pii(a[i], i));
                ps.eb(i, i + 1);
            } else {
                s.back().insert(pii(a[i], i));
                ps.back().second++;
            }

            while (true) {
                K = sz(s);
                if (K >= 2 && s[K - 1].median().first <= s[K - 2].median().first) {
                    if (s[K - 2].size() < s[K - 1].size()) {
                        swap(s[K - 2], s[K - 1]);
                        swap(ps[K - 2], ps[K - 1]);
                    }
                    rep2(j, ps[K - 1].first, ps[K - 1].second) {
                        s[K - 2].insert(pii(a[j], j)); //
                    }
                    chmin(ps[K - 2].first, ps[K - 1].first);
                    chmax(ps[K - 2].second, ps[K - 1].second);
                    s.pop_back(), ps.pop_back();
                } else {
                    break;
                }
            }
        }

        // cout << "! " << i << '\n';
        // rep(i, sz(s)) {
        //     cout << ps[i] MM s[i].size() MM s[i].median() << '\n';
        //     cout << ps[i] << '\n';
        // }
    }

    int K = sz(s);
    ll ans = 0;
    rep(i, K) {
        auto [l, r] = ps[i];
        ll x = s[i].median().first;
        // cout << l MM r MM x << '\n';
        rep2(j, l, r) ans += abs(a[j] - x);
    }

    cout << ans << '\n';
}

int main() {
    int T = 1;
    // cin >> T;
    while (T--) solve();
}