#include <bits/stdc++.h>
#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")
using namespace std;
using std::cout;
using std::cin;
using std::endl;
using ll=long long;
using ld=long double;
ll ILL=2167167167167167167;
const int INF=2100000000;
const int mod=998244353;
#define rep(i,a,b) for (ll i=a;i<b;i++)
#define all(p) p.begin(),p.end()
template<class T> using _pq = priority_queue<T, vector<T>, greater<T>>;
template<class T> ll LB(vector<T> &v,T a){return lower_bound(v.begin(),v.end(),a)-v.begin();}
template<class T> ll UB(vector<T> &v,T a){return upper_bound(v.begin(),v.end(),a)-v.begin();}
template<class T> bool chmin(T &a,const T &b){if(a>b){a=b;return 1;}else return 0;}
template<class T> bool chmax(T &a,const T &b){if(a<b){a=b;return 1;}else return 0;}
template<class T> void So(vector<T> &v) {sort(v.begin(),v.end());}
template<class T> void Sore(vector<T> &v) {sort(v.begin(),v.end(),[](T x,T y){return x>y;});}
void yneos(bool a){if(a) cout<<"Yes\n"; else cout<<"No\n";}
template<class T> void vec_out(vector<T> &p){for(int i=0;i<(int)(p.size());i++){if(i) cout<<" ";cout<<p[i];}cout<<"\n";}
template<class T> T vec_min(vector<T> &a){assert(!a.empty());T ans=a[0];for(auto &x:a) chmin(ans,x);return ans;}
template<class T> T vec_max(vector<T> &a){assert(!a.empty());T ans=a[0];for(auto &x:a) chmax(ans,x);return ans;}
template<class T> T vec_sum(vector<T> &a){assert(!a.empty());T ans=a[0]-a[0];for(auto &x:a) ans+=x;return ans;}
int pop_count(long long a){int res=0;while(a){res+=(a&1),a>>=1;}return res;}

namespace po167{
template<class T>
struct slope_trick{
	std::priority_queue<T> left_pq;
	std::priority_queue<T,std::vector<T>,std::greater<T>> right_pq;
	T min_f;
	T add_l,add_r;
	slope_trick():min_f(0),add_l(0),add_r(0){};
	
	//f(x)=min(f(i)) i<=x
	void left_min(){
		right_pq={};
		add_r=0;
	}
	//f(x)=min(f(i)) i>=x
	void right_min(){
		left_pq={};
		add_l=0;
	}
	void add_constant_function(T d){
		min_f+=d;
	}
	//f(x)<- f(x)+max(x-a,0)
	void add_x_minus_a(T a){
		a-=add_l;
		if(!left_pq.empty()){
			min_f+=std::max(left_pq.top()-a,(T)0);
		}
		left_pq.push(a);
		right_pq.push(left_pq.top()+add_l-add_r);
		left_pq.pop();
	}

	//f(x) <- f(x)+max(a-x,0)
	void add_a_minus_x(T a){
		a-=add_r;
		if(!right_pq.empty()){
			min_f+=std::max(a-right_pq.top(),(T)0);
		}
		right_pq.push(a);
		left_pq.push(right_pq.top()+add_r-add_l);
		right_pq.pop();
	}

	//f(x) <- f(x) + |x-a|
	void add_abs_x_minus_a(T a){
		add_a_minus_x(a);
		add_x_minus_a(a);
	}

	//f(x) <- f(x-a)
	void shift(T a){
		add_l+=a;
		add_r+=a;
	}

	//f(x) <- min(f(x-i)) i= a~b
	//need: a<=b
	void sliding_min(T a,T b){
		assert(a<=b);
		add_l+=a;
		add_r+=b;
	}

    void merge_and_break(slope_trick &S){
		min_f+=S.min_f;
		T tmp;
		while(!S.left_pq.empty()){
			tmp=S.left_pq.top();
			S.left_pq.pop();
			add_a_minus_x(S.add_l+tmp);
		}
		while(!S.right_pq.empty()){
			tmp=S.right_pq.top();
			S.right_pq.pop();
			add_x_minus_a(S.add_r+tmp);
		}
	}
	void merge_and_remain(slope_trick S){
		merge_and_break(S);
	}
};
}
using po167::slope_trick;


void solve();
// oddloop
int main() {
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	
	int t=1;
	//cin>>t;
	rep(i,0,t) solve();
}

void solve(){
	int N;
	cin>>N;
	vector<ll> A(N);
	rep(i,0,N) cin>>A[i];
	slope_trick<ll> S;
	So(A);
	rep(i,0,N){
		S.left_min();
		S.add_abs_x_minus_a(A[i]-i);
	}
	cout<<S.min_f<<"\n";
}