import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.math.BigInteger;
import java.util.ArrayList;
import java.util.Random;
import java.util.StringTokenizer;


public class Main {

	static boolean visited[] ; 
	static boolean ends[] ;
	static int lens[] ; 
	static int seeds[] ; 
	static int a[] ;
	static double total ; 
	public static ArrayList adj[] ; 

	public static void main(String[] args) throws IOException, InterruptedException {
		Scanner sc  = new Scanner(System.in) ;
		int n = sc.nextInt() ; 
		a = new int[n/2] ;
		int tot = 0 ; 
		for (int i = 0; i < a.length; i++)
		{
			a[i]=sc.nextInt()-1 ; 
		}
		int blackM =0 ; 
		int whiteM= 0 ;

		for (int i = 0, j=0; i < n; i+=2)
		{
			blackM+= Math.abs(i-a[j++]);
		}

		for (int i = 1,j=0; i < n; i+=2)
		{
			whiteM+= Math.abs(i-a[j++]);
		}


		System.err.println(blackM);
		System.err.println(whiteM);

		System.out.println(Math.min(blackM, whiteM));


	}










	public static void dfss(int root , int len)
	{
		visited[root]=true ; 
		if(ends[root] && root!=0) lens[root] = len ; 

		for (int i = 0; i < adj[root].size(); i++)
		{
			int c= (int) adj[root].get(i) ; 
			if(visited[c]==false)
				dfss(c, len+1);
		}
	}

	public static void pr(int root ,  int seed){
		visited[root] = true ;
		int dv = adj[root].size()-1 ; 
		if(root==0) dv++ ;

		for (int i = 0; i < adj[root].size(); i++)
		{
			int c = (int)adj[root].get(i) ; 
			seeds[c]=dv*seed ;
		}

		for (int i = 0; i < adj[root].size() ; i++)
		{
			int c = (int)adj[root].get(i) ; 
			if(visited[c]==false)
				pr(c , seeds[c]);

		}

	}


	public static String concatinate(String s ,int n)
	{
		if(s.length()==n)
			return s ; 
		else return concatinate("0"+s, n) ;
	}
	static class Scanner {
		StringTokenizer st;
		BufferedReader br;

		public Scanner(InputStream s) {
			br = new BufferedReader(new InputStreamReader(s));
		}

		public String next() throws IOException {
			while (st == null || !st.hasMoreTokens())
				st = new StringTokenizer(br.readLine());
			return st.nextToken();
		}

		public int nextInt() throws IOException {
			return Integer.parseInt(next());
		}

		public long nextLong() throws IOException {
			return Long.parseLong(next());
		}

		public String nextLine() throws IOException {
			return br.readLine();
		}

		public double nextDouble() throws IOException {
			return Double.parseDouble(next());
		}

		public boolean ready() throws IOException {
			return br.ready();
		}
	}


	public static long getGCD(long n1, long n2) {
		if (n2 == 0) {
			return n1;
		}
		return getGCD(n2, n1 % n2);
	}

	public static int cnt1(int mat[][])  //how many swaps to be a 1 matrix
	{
		int m = mat.length ; 
		int c=0 ; 
		for (int i = 0; i < mat.length; i++)
		{
			for (int j = 0; j < mat.length; j++)
			{
				int x =  (i*m) +j ;
				if(x%2==0 && mat[i][j]==0)
					c++; 
				if(x%2!=0 && mat[i][j]==1)
					c++; 

			}
		}
		return c;
	}
	public static int cnt0(int mat[][])
	{
		int m = mat.length ; 
		int c=0 ; 
		for (int i = 0; i < mat.length; i++)
		{
			for (int j = 0; j < mat.length; j++)
			{
				int x =  (i*m) +j ; 
				if(x%2!=0 && mat[i][j]==0)
					c++; 
				if(x%2==0 && mat[i][j]==1)
					c++; 

			}
		}
		return c;
	}

	public static boolean canFit2(int x1, int y1 , int x2 , int y2 , int x3 , int y3){
		if(x1==x2)
			if(x1==x3)
				return true ; 
			else
				return false ;
		else
			if(x1==x3)
				return false ; 
			else
			{
				long a = 1l*(y2-y1)*(x3-x2) ; 
				long b = 1l*(y3-y2)*(x2-x1) ; 

				if(a==b)
					return true;
				else 
					return false ;

			}

	}
	public static void shuffle(int c[]){
		if(c.length==1)
			return ; 
		for (int i = 0; i < c.length; i++)
		{
			Random rand = new Random();

			int  n = rand.nextInt(c.length-1) + 0;

			int temp = c[i] ; 
			c[i] = c[n] ; 
			c[n] = temp ;
		}
	}
	public static int binary(long[]arr, int l, int r, long x)   /// begin by 0 and n-1
	{
		if (r>=l)
		{
			int mid = l + (r - l)/2;
			if (arr[mid]== x)
				return mid;
			if (arr[mid]> x)
				return binary(arr, l, mid-1, x);
			return binary(arr, mid+1, r, x);
		}
		return -1;
	}

	/// searching for the index of first elment greater than x
	public static int binary1(long[]arr , long x) {
		int low = 0, high = arr.length; // numElems is the size of the array i.e arr.size() 
		while (low != high) {
			int mid = (low + high) / 2; // Or a fancy way to avoid int overflow
			if (arr[mid] <= x) {
				/* This index, and everything below it, must not be the first element
				 * greater than what we're looking for because this element is no greater
				 * than the element.
				 */
				low = mid + 1;
			}
			else {
				/* This element is at least as large as the element, so anything after it can't
				 * be the first element that's at least as large.
				 */
				high = mid;
			}
		}
		return low ; // return high ; 
	}


	private static boolean triangle(int a, int b , int c){
		if(a+b>c && a+c>b && b+c>a)
			return true ; 
		else 
			return false ;
	}
	private static boolean segment(int a, int b , int c){
		if(a+b==c || a+c==b && b+c==a)
			return true ; 
		else 
			return false ;
	}
	private static int gcdThing(long a, long b) {
		BigInteger b1 = BigInteger.valueOf(a);
		BigInteger b2 = BigInteger.valueOf(b);
		BigInteger gcd = b1.gcd(b2);
		return gcd.intValue();
	}

	public static boolean is(int i){
		if(Math.log(i)/ Math.log(2) ==(int) (Math.log(i)/ Math.log(2)))
			return true ; 
		if(Math.log(i)/ Math.log(3) ==(int) (Math.log(i)/ Math.log(3)) )
			return true ; 
		if(Math.log(i)/ Math.log(6) ==(int) (Math.log(i)/ Math.log(6)) )
			return true ; 

		return false;

	}
	public static boolean contains(int b[] , int x)
	{
		for (int i = 0; i < b.length; i++)
		{
			if(b[i]==x)
				return true ;
		}
		return false ;
	}
	public static int binary(long []arr , long target , int low , long shift) {
		int high = arr.length; 
		while (low != high) {
			int mid = (low + high) / 2; 
			if (arr[mid]-shift <= target) {
				low = mid + 1;
			}
			else {
				high = mid;
			}
		}
		return low ; // return high ; 
	}
	public static boolean isLetter(char x){
		if(x+0 <=122 && x+0 >=97 )
			return true ;
		else if (x+0 <=90 && x+0 >=65 )
			return true ; 
		else return false; 
	}
	public static long getPrimes(long x ){
		if(x==2 || x==3 || x==1)
			return 2 ;
		if(isPrime(x))
			return 5 ;
		for (int i = 2; i*i<=x; i++)
		{
			if(x%i==0 && isPrime(i))
				return getPrimes(x/i) ;
		}
		return -1;
	}
	public static String solve(String x){

		int n = x.length() ; 
		String y = "" ;
		for (int i = 0; i < n-2; i+=2)
		{
			if(ifPalindrome(x.substring(i, i+2)))
				y+= x.substring(i, i+2) ;
			else 
				break ;
		}
		return y+ solve1(x.substring(y.length(),x.length())) ;

	}
	public static String solve1(String x){
		String y = x.substring(0 , x.length()/2) ; 
		return "" ;

	}
	public static String reverse(String x){
		String y ="" ;
		for (int i = 0; i < x.length(); i++)
		{
			y  = x.charAt(i) + y ;
		}
		return y ;
	}

	public static boolean ifPalindrome(String x){
		int numbers[] = new int[10] ; 
		for (int i = 0; i < x.length(); i++)
		{
			int z = Integer.parseInt(x.charAt(i)+"") ; 
			numbers[z] ++ ;
		}
		for (int i = 0; i < numbers.length; i++)
		{
			if(numbers[i]%2!=0)
				return false; 
		}
		return true ;	
	}

	public static int get(int n){
		return n*(n+1)/2 ; 
	}
	//		public static long getSmallestDivisor( long y){
	//			if(isPrime(y))
	//				return -1;
	//
	//			for (long i = 2; i*i <= y; i++)
	//			{
	//				if(y%i ==0)
	//				{
	//					return i;
	//				}
	//			}
	//			return -1;
	//		}
	//		public static void lis( []a , int n){
	//			int lis[] = new int[n] ; 
	//			Arrays.fill(lis,1) ; 
	//
	//			for(int i=1;i<n;i++)
	//				for(int j=0 ; j<i; j++)
	//					if (a[i].y>a[j].y &&  lis[i] < lis[j]+1)   
	//						lis[i] = lis[j] + 1;           
	//
	//			int max = lis[0];
	//
	//			for(int i=1; i<n ; i++)
	//				if (max < lis[i])
	//					max = lis[i] ;
	//			System.out.println(max);
	//
	//			ArrayList<Integer> s = new ArrayList<Integer>() ;
	//			for (int i = n-1; i >=0; i--)
	//			{
	//				if(lis[i]==max)
	//				{
	//					s.add(a[i].z);
	//					max --; 
	//				}
	//			}
	//
	//			for (int i = s.size()-1 ; i>=0 ;  i--)
	//			{
	//				System.out.print(s.get(i)+" ");
	//			}
	//
	//			return  ; 
	//		}
	public static int calcDepth(Vertix node){
		if(node.depth>0) return node.depth; 
		// meaning it has been updated before;
		if(node.parent != null)
			return 1+ calcDepth(node.parent);
		else
			return -1;
	}

	public static boolean isPrime (long num){
		if (num < 2) return false;
		if (num == 2) return true;
		if (num % 2 == 0) return false;
		for (int i = 3; i * i <= num; i += 2)
			if (num % i == 0) return false;
		return true;
	}


	public static ArrayList<Long> getDiv(Long n)
	{
		ArrayList<Long>  f = new ArrayList<Long>() ; 

		while (n%2==0)
		{
			if(!f.contains(2))f.add((long) 2) ;
			n /= 2;
		}

		// n must be odd at this point.  So we can
		// skip one element (Note i = i +2)
		for (long i = 3; i <= Math.sqrt(n); i+= 2)
		{
			// While i divides n, print i and divide n
			while (n%i == 0)
			{
				if(!f.contains(i))f.add(i);
				n /= i;
			}
		}

		// This condition is to handle the case whien
		// n is a prime number greater than 2
		if (n > 2)
			if(!f.contains(n))f.add(n);


		return f ;



	}

	//		public static boolean dfs(Vertix v , int target){
	//			try{
	//				visited[v.i]= true ;
	//			} catch (NullPointerException e)
	//			{
	//				System.out.println(v.i);
	//			}
	//			if(v.i == target)
	//
	//				return true ;
	//			for (int i =0 ; i< v.neighbours.size() ; i++)
	//			{ 
	//
	//				Vertix child = v.neighbours.get(i) ;
	//				if(child.i == target){
	//					found = true  ; 
	//				}
	//				if(visited[child.i]==false){
	//					found |= dfs(child, target) ;
	//				}
	//			}
	//			return found; 
	//		}









	public static class Vertix{
		long i ; 
		int depth ;
		ArrayList<Vertix> neighbours ; 
		Vertix parent ; 
		Vertix child ; 


		public Vertix(long i){
			this.i = i ;
			this.neighbours = new ArrayList<Vertix> () ;
			this.parent = null ;
			depth =-1;
			this.child = null ;
		}
	}

	public static class pair{
		int p ; 
		int x ;
		int y ;





		public pair(int p,int x, int y ){
			this.p=p;
			this.x=x ; 
			this.y=y ;


		}
		public boolean equals(pair s)
		{
			if(this.p==s.p && this.x==s.x && this.y==s.y)
				return true;
			else 
				return false;

		}





	}

	public static class pair2 implements Comparable<pair2>{
		int i ; 
		int j ;
		int index ; 

		public pair2(int i , int j , int index){
			this.i =i ;
			this.j = j ; 
			this.index = index ;
		}

		@Override
		public int compareTo(pair2 p) {
			if(this.j > p.j)
				return 1 ; 
			else if (this.j == p.j) return 0 ;
			else 
				return -1 ;
		}


	}


}