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.util.*;
public class S
{
    public static void main(String [] args)
    {
        Scanner obj = new Scanner(System.in);
        int n=obj.nextInt();
         int k=1,t=2;
         if(n%2!=0)
             {
                 System.out.println("-1");
                 System.exit(0);
             }
         for(int i=1;i<=n;i++)
         {
             if(i%2==0)
              {
                  System.out.print(k+" ");
                  k=k+2;
              }
              else
              {
                  System.out.print(t+" ");
                  t=t+2;
              }
         }
    }
}