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.*;
import java.math.*;

public class codeforces
{
	  public static void main(String[] args)throws IOException
	  {
	  	   BufferedReader br = new BufferedReader(new InputStreamReader(System.in));


           Scanner sc = new Scanner(System.in);
           int n = Integer.parseInt(br.readLine());

           if(n%2!=0)
           {
           	      System.out.print(-1);
           }
           else
           {
           	      int k=2;
           	      while(n>0)
           	      {
           	      	     n=n-2;
           	      	     System.out.print(k+" "+ (k-1)+" ");
           	      	     k+=2;
           	      }
           }


            

            







      }
     

	  
	  
}