Problem: A permutation is a sequence of integers p1, p2, ..., pn, consisting of n distinct positive integers, each of them doesn't exceed n. Let's denote the i-th element of permutation p as pi. We'll call number n the size of permutation p1, p2, ..., pn.

Nickolas adores permutations. He likes some permutations more than the others. He calls such permutations perfect. A perfect permutation is such permutation p that for any i (1 ≤ i ≤ n) (n is the permutation size) the following equations hold ppi = i and pi ≠ i. Nickolas asks you to print any perfect permutation of size n for the given n.

Input

A single line contains a single integer n (1 ≤ n ≤ 100) — the permutation size.

Output

If a perfect permutation of size n doesn't exist, print a single integer -1. Otherwise print n distinct integers from 1 to n, p1, p2, ..., pn — permutation p, that is perfect. Separate printed numbers by whitespaces.

Examples

Input

1


Output

-1


Input

2


Output

2 1 


Input

4


Output

2 1 4 3 

Solution (in JAVA):

Solution:

import java.io.*;
import java.util.*;

public class Main {
    



    public static void main(String args[]) throws IOException {
            Reader.init(System.in);
        int n = Reader.nextInt(); 
          if (n % 2 != 0 ){
              System.out.println("-1");
    }
          else
          {
              for(int i = 1   ;  i  <n ; i+=2){
                  System.out.print(i+1+" ");
                  System.out.print(i+" ");
              }
          }
    }
        
}
class laptops implements Comparable<laptops>{
        int price ,quilty; 
    
        public laptops (int p , int q)
        {
            this.price = p ; 
            this.quilty = q ;
        }

        @Override
        public int compareTo(laptops o) {
            return Integer.compare(this.price, o.price);
        }
        
    }

 

class Reader {

    static BufferedReader reader;
    static StringTokenizer tokenizer;

    /**
     * call this method to initialize reader for InputStream
     */
    static void init(InputStream input) {
        reader = new BufferedReader(
                new InputStreamReader(input));
        tokenizer = new StringTokenizer("");
    }

    /**
     * get next word
     */
    static String next() throws IOException {
        while (!tokenizer.hasMoreTokens()) {
            //TODO add check for eof if necessary
            tokenizer = new StringTokenizer(
                    reader.readLine());
        }
        return tokenizer.nextToken();
    }

    static int nextInt() throws IOException {
        return Integer.parseInt(next());
    }
    static long nextLong() throws IOException {
        return Long.parseLong(next());
    }

    static double nextDouble() throws IOException {
        return Double.parseDouble(next());
    }
   static public void nextIntArrays(int[]... arrays) throws IOException {
        for (int i = 1; i < arrays.length; ++i) {
            if (arrays[i].length != arrays[0].length) {
                throw new InputMismatchException("Lengths are different");
            }
        }
        for (int i = 0; i < arrays[0].length; ++i) {
            for (int[] array : arrays) {
                array[i] = nextInt();
            }
        }}
    static public void nextLineArrays(String[]... arrays) throws IOException {
        for (int i = 1; i < arrays.length; ++i) {
            if (arrays[i].length != arrays[0].length) {
                throw new InputMismatchException("Lengths are different");
            }
        }
        for (int i = 0; i < arrays[0].length; ++i) {
            for (String[] array : arrays) {
                array[i] = reader.readLine();
            }
        }}
}