#include <bits/stdc++.h>
using namespace std;
using ll = long long;

struct dsu {
    public:
    int csz;
    dsu() : _n(0) {}
    dsu(int n) : _n(n), csz(n), parent_or_size(n, -1) {}

    int merge(int a, int b) {
        assert(0 <= a && a < _n);
        assert(0 <= b && b < _n);
        int x = leader(a), y = leader(b);
        if (x == y) return x;
        if (-parent_or_size[x] < -parent_or_size[y]) std::swap(x, y);
        csz--;
        parent_or_size[x] += parent_or_size[y];
        parent_or_size[y] = x;
        return x;
    }

    bool same(int a, int b) {
        assert(0 <= a && a < _n);
        assert(0 <= b && b < _n);
        return leader(a) == leader(b);
    }

    int leader(int a) {
        assert(0 <= a && a < _n);
        if (parent_or_size[a] < 0) return a;
        return parent_or_size[a] = leader(parent_or_size[a]);
    }

    int size(int a) {
        assert(0 <= a && a < _n);
        return -parent_or_size[leader(a)];
    }

    std::vector<std::vector<int>> groups() {
        std::vector<int> leader_buf(_n), group_size(_n);
        for (int i = 0; i < _n; i++) {
            leader_buf[i] = leader(i);
            group_size[leader_buf[i]]++;
        }
        std::vector<std::vector<int>> result(_n);
        for (int i = 0; i < _n; i++) {
            result[i].reserve(group_size[i]);
        }
        for (int i = 0; i < _n; i++) {
            result[leader_buf[i]].push_back(i);
        }
        result.erase(
            std::remove_if(result.begin(), result.end(),
                           [&](const std::vector<int>& v) { return v.empty(); }),
            result.end());
        return result;
    }

    private:
    int _n;
    // root node: -1 * component size
    // otherwise: parent
    std::vector<int> parent_or_size;
};

template<class T> struct median_priority_queue {
    std::priority_queue<T> pqL;
    std::priority_queue<T, std::vector<T>, std::greater<T>> pqR; 
    median_priority_queue() {
        //pqL.emplace(std::numeric_limits<T>::min());
        //pqR.emplace(std::numeric_limits<T>::max());
    }
    void push(T v){
        if(!pqL.empty() && v < pqL.top()) pqL.emplace(v);
        else pqR.emplace(v);
        update();
    }
    T get(){
        return pqR.top();
    }
    int size(){
        return int(pqL.size() + pqR.size());
    }
    void update(){
        while(pqL.size() + 2 <= pqR.size()){
            pqL.emplace(pqR.top());
            pqR.pop();
        }
        while(pqL.size() > pqR.size()){
            pqR.emplace(pqL.top());
            pqL.pop();
        }
    }
};

int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    int n;
    cin >> n;
    dsu uf(n);
    vector<int> a(n), b(n);
    vector<median_priority_queue<int>> pq(n);
    for(auto &&v : a) cin >> v;
    sort(a.begin(), a.end());
    auto merge = [&](int i, int j){
        if(pq[i].size() < pq[j].size()){
            swap(pq[i], pq[j]);
            swap(i, j);
        }
        uf.merge(i, j);
        auto &tmp = pq[j].pqR;
        while(!tmp.empty()){
            pq[i].push(tmp.top());
            tmp.pop();
        }
        auto &tmp2 = pq[j].pqL;
        while(!tmp2.empty()){
            pq[i].push(tmp2.top());
            tmp2.pop();
        }
    };
    stack<int> st;
    for(int i = 0; i < n; i++){
        b[i] = a[i] - i;
        pq[i].push(b[i]);
        st.emplace(i);
    }
    for(int i = 0; i + 1 < n; i++){
        if(b[i] == b[i + 1]) merge(i, i + 1);
    }
    while(st.size() >= 2){
        int i = uf.leader(st.top());
        st.pop();
        int j = uf.leader(st.top());
        if(i == j) continue;
        if(pq[j].get() > pq[i].get()) merge(i, j);
    }
    ll ans = 0;
    for(int i = 0; i < n; i++){
        ans += abs(b[i] - pq[uf.leader(i)].get());
    }
    cout << ans << '\n';
}