
import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.StringTokenizer; 

public class Main { 
	
	
	
	
	public static void main(String[] args) {
        InputReader reader = new InputReader(System.in);
       
   int n = reader.nextInt();
   int length = n/2;

ArrayList<Integer> myPos = new ArrayList<>();
ArrayList<Integer> myEven = new ArrayList<>();
ArrayList<Integer> myOdd = new ArrayList<>();
 for(int i = 1;i<=n;i++) {
	 if(i%2==0) {
		 myEven.add(i);
	 }
	 else {
		 myOdd.add(i);
	 }
 }
   
   
   int countEvenWay = 0;
   int countOddWay = 0;
   for(int i =0;i<length;i++) {
	  myPos.add(reader.nextInt());
	   countEvenWay+=Math.abs((myEven.get(i)-myPos.get(i)));
	   countOddWay+=Math.abs((myOdd.get(i)-myPos.get(i)));
   }
  

  
  if(countEvenWay<countOddWay) {
	  System.out.println(countEvenWay);
  }
  else {
	  System.out.println(countOddWay);
  }
   
   
  
        
    }
    static class InputReader {

        StringTokenizer tokenizer;
        BufferedReader reader;
        String token;
        String temp;

        public InputReader(InputStream stream) {
            tokenizer = null;
            reader = new BufferedReader(new InputStreamReader(stream));
        }

        public InputReader(FileInputStream stream) {
            tokenizer = null;
            reader = new BufferedReader(new InputStreamReader(stream));
        }

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

        public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    if (temp != null) {
                        tokenizer = new StringTokenizer(temp);
                        temp = null;
                    } else {
                        tokenizer = new StringTokenizer(reader.readLine());
                    }

                } catch (IOException e) {
                }
            }
            return tokenizer.nextToken();
        }

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

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

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