import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.StringTokenizer;

public class zizo {

	public static void main(String[]args) throws IOException {
		Scanner zizo=new Scanner(System.in);
		PrintWriter wr=new PrintWriter(System.out);
		
		int n=zizo.nextInt();
		int c=0;
		int[]arr=new int[n/2];
		for(int i=0;i<n/2;i++) {
			arr[i]=zizo.nextInt();
		}
		int x=1;
		for(int i=0;i<n/2;i++) {
			c+=Math.abs(arr[i]-x);
			x+=2;
		}
		int r=0;
		x=2;
		for(int i=0;i<n/2;i++) {
			r+=Math.abs(arr[i]-x);
			x+=2;
		}
		wr.println(Math.min(r, c));
		wr.close();
	}
}

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

	public double nextDouble() throws IOException 
	{
		String x = next();
		StringBuilder sb = new StringBuilder("0");
		double res = 0, f = 1;
		boolean dec = false, neg = false;
		int start = 0;
		if(x.charAt(0) == '-')
		{
			neg = true;
			start++;
		}
		for(int i = start; i < x.length(); i++)
			if(x.charAt(i) == '.')
			{
				res = Long.parseLong(sb.toString());
				sb = new StringBuilder("0");
				dec = true;
			}
			else
			{
				sb.append(x.charAt(i));
				if(dec)
					f *= 10;
			}
		res += Long.parseLong(sb.toString()) / f;
		return res * (neg?-1:1);
	}


}