//package CodeForces;

/*In the name of Allah the Most Merciful.
 * Author
 * Md. Toufiqul Islam
 * Dept. Of CSE
 * Ahsanullah University Of Science And Technology
*/


import java.io.*;
import java.util.*;
import java.math.*;
public class E44A {
    public static void main(String[] args) {
        InputReader sc = new InputReader(System.in);
        OutputWriter out = new OutputWriter(System.out);
        int n = sc.nextInt();
       ArrayList<Integer> list = new ArrayList<>();

        for(int i=0;i<n/2;i++){
            list.add(sc.nextInt());
        }

        List<Integer> allW = new ArrayList<>();
        for(int i=1;i<=n;i++){
            if(i%2==0){
                allW.add(i);
            }
        }

        int totalForW = 0;

        for(int i=0;i<list.size();i++){
            totalForW += Math.abs(list.get(i)-allW.get(i));
        }

        List<Integer> allB = new ArrayList<>();
        for(int i=1;i<=n;i++){
            if(i%2!=0){
                allB.add(i);
            }
        }

        int totalForB = 0;

        for(int i=0;i<list.size();i++){
            totalForB += Math.abs(list.get(i)-allB.get(i));
        }

        out.println(Math.min(totalForB,totalForW));

        out.close();
    }

     public static class InputReader {
             private boolean finished = false;

             private InputStream stream;
             private byte[] buf = new byte[1024];
             private int curChar;
             private int numChars;
             private SpaceCharFilter filter;

             public InputReader(InputStream stream) {
                 this.stream = stream;
             }

             public int read() {
                 if (numChars == -1) {
                     throw new InputMismatchException();
                 }
                 if (curChar >= numChars) {
                     curChar = 0;
                     try {
                         numChars = stream.read(buf);
                     } catch (IOException e) {
                         throw new InputMismatchException();
                     }
                     if (numChars <= 0) {
                         return -1;
                     }
                 }
                 return buf[curChar++];
             }

             public int peek() {
                 if (numChars == -1) {
                     return -1;
                 }
                 if (curChar >= numChars) {
                     curChar = 0;
                     try {
                         numChars = stream.read(buf);
                     } catch (IOException e) {
                         return -1;
                     }
                     if (numChars <= 0) {
                         return -1;
                     }
                 }
                 return buf[curChar];
             }

             public int nextInt() {
                 int c = read();
                 while (isSpaceChar(c)) {
                     c = read();
                 }
                 int sgn = 1;
                 if (c == '-') {
                     sgn = -1;
                     c = read();
                 }
                 int res = 0;
                 do {
                     if (c < '0' || c > '9') {
                         throw new InputMismatchException();
                     }
                     res *= 10;
                     res += c - '0';
                     c = read();
                 } while (!isSpaceChar(c));
                 return res * sgn;
             }

             public long nextLong() {
                 int c = read();
                 while (isSpaceChar(c)) {
                     c = read();
                 }
                 int sgn = 1;
                 if (c == '-') {
                     sgn = -1;
                     c = read();
                 }
                 long res = 0;
                 do {
                     if (c < '0' || c > '9') {
                         throw new InputMismatchException();
                     }
                     res *= 10;
                     res += c - '0';
                     c = read();
                 } while (!isSpaceChar(c));
                 return res * sgn;
             }

             public String nextString() {
                 int c = read();
                 while (isSpaceChar(c)) {
                     c = read();
                 }
                 StringBuilder res = new StringBuilder();
                 do {
                     if (Character.isValidCodePoint(c)) {
                         res.appendCodePoint(c);
                     }
                     c = read();
                 } while (!isSpaceChar(c));
                 return res.toString();
             }

             public boolean isSpaceChar(int c) {
                 if (filter != null) {
                     return filter.isSpaceChar(c);
                 }
                 return isWhitespace(c);
             }

             public static boolean isWhitespace(int c) {
                 return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
             }

             private String readLine0() {
                 StringBuilder buf = new StringBuilder();
                 int c = read();
                 while (c != '\n' && c != -1) {
                     if (c != '\r') {
                         buf.appendCodePoint(c);
                     }
                     c = read();
                 }
                 return buf.toString();
             }

             public String readLine() {
                 String s = readLine0();
                 while (s.trim().length() == 0) {
                     s = readLine0();
                 }
                 return s;
             }

             public String readLine(boolean ignoreEmptyLines) {
                 if (ignoreEmptyLines) {
                     return readLine();
                 } else {
                     return readLine0();
                 }
             }

             public BigInteger readBigInteger() {
                 try {
                     return new BigInteger(nextString());
                 } catch (NumberFormatException e) {
                     throw new InputMismatchException();
                 }
             }

             public char nextCharacter() {
                 int c = read();
                 while (isSpaceChar(c)) {
                     c = read();
                 }
                 return (char) c;
             }

             public double nextDouble() {
                 int c = read();
                 while (isSpaceChar(c)) {
                     c = read();
                 }
                 int sgn = 1;
                 if (c == '-') {
                     sgn = -1;
                     c = read();
                 }
                 double res = 0;
                 while (!isSpaceChar(c) && c != '.') {
                     if (c == 'e' || c == 'E') {
                         return res * Math.pow(10, nextInt());
                     }
                     if (c < '0' || c > '9') {
                         throw new InputMismatchException();
                     }
                     res *= 10;
                     res += c - '0';
                     c = read();
                 }
                 if (c == '.') {
                     c = read();
                     double m = 1;
                     while (!isSpaceChar(c)) {
                         if (c == 'e' || c == 'E') {
                             return res * Math.pow(10, nextInt());
                         }
                         if (c < '0' || c > '9') {
                             throw new InputMismatchException();
                         }
                         m /= 10;
                         res += (c - '0') * m;
                         c = read();
                     }
                 }
                 return res * sgn;
             }

             public boolean isExhausted() {
                 int value;
                 while (isSpaceChar(value = peek()) && value != -1) {
                     read();
                 }
                 return value == -1;
             }

             public String next() {
                 return nextString();
             }

             public SpaceCharFilter getFilter() {
                 return filter;
             }

             public void setFilter(SpaceCharFilter filter) {
                 this.filter = filter;
             }

             public interface SpaceCharFilter {
                 public boolean isSpaceChar(int ch);
             }
             public int[] nextIntArray(int n){
                 int[] array=new int[n];
                 for(int i=0;i<n;++i)array[i]=nextInt();
                 return array;
             }
             public int[] nextSortedIntArray(int n){
                 int array[]=nextIntArray(n);
                 Arrays.sort(array);
                 return array;
             }
             public int[] nextSumIntArray(int n){
                 int[] array=new int[n];
                 array[0]=nextInt();
                 for(int i=1;i<n;++i)array[i]=array[i-1]+nextInt();
                 return array;
             }
             public long[] nextLongArray(int n){
                 long[] array=new long[n];
                 for(int i=0;i<n;++i)array[i]=nextLong();
                 return array;
             }
             public long[] nextSumLongArray(int n){
                 long[] array=new long[n];
                 array[0]=nextInt();
                 for(int i=1;i<n;++i)array[i]=array[i-1]+nextInt();
                 return array;
             }
             public long[] nextSortedLongArray(int n){
                 long array[]=nextLongArray(n);
                 Arrays.sort(array);
                 return array;
             }
         }
      public static class OutputWriter {
              private final PrintWriter writer;

              public OutputWriter(OutputStream outputStream) {
                  writer = new PrintWriter(new BufferedWriter(new OutputStreamWriter(outputStream)));
              }

              public OutputWriter(Writer writer) {
                  this.writer = new PrintWriter(writer);
              }

              public void print(char[] array) {
                  writer.print(array);
              }

              public void print(Object... objects) {
                  for (int i = 0; i < objects.length; i++) {
                      if (i != 0) {
                          writer.print(' ');
                      }
                      writer.print(objects[i]);
                  }
              }

              public void print(int[] array) {
                  for (int i = 0; i < array.length; i++) {
                      if (i != 0) {
                          writer.print(' ');
                      }
                      writer.print(array[i]);
                  }
              }

              public void print(double[] array) {
                  for (int i = 0; i < array.length; i++) {
                      if (i != 0) {
                          writer.print(' ');
                      }
                      writer.print(array[i]);
                  }
              }

              public void print(long[] array) {
                  for (int i = 0; i < array.length; i++) {
                      if (i != 0) {
                          writer.print(' ');
                      }
                      writer.print(array[i]);
                  }
              }

              public void println(int[] array) {
                  print(array);
                  writer.println();
              }

              public void println(double[] array) {
                  print(array);
                  writer.println();
              }

              public void println(long[] array) {
                  print(array);
                  writer.println();
              }

              public void println() {
                  writer.println();
              }

              public void println(Object... objects) {
                  print(objects);
                  writer.println();
              }

              public void print(char i) {
                  writer.print(i);
              }

              public void println(char i) {
                  writer.println(i);
              }

              public void println(char[] array) {
                  writer.println(array);
              }

              public void printf(String format, Object... objects) {
                  writer.printf(format, objects);
              }

              public void close() {
                  writer.close();
              }

              public void flush() {
                  writer.flush();
              }

              public void print(long i) {
                  writer.print(i);
              }

              public void println(long i) {
                  writer.println(i);
              }

              public void print(int i) {
                  writer.print(i);
              }

              public void println(int i) {
                  writer.println(i);
              }

              public void separateLines(int[] array) {
                  for (int i : array) {
                      println(i);
                  }
              }
          }

}
