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 Main
 {
     
     public static void main(String args[])
      {
        Scanner scn=new Scanner(System.in);
        int n=scn.nextInt();
        
        int [] arr=new int[n];
        
        for(int i=0;i<n;i++)
         {
          arr[i]=i+1;
         }
        if(n%2!=0)
         {
          System.out.println("-1");
         }
         
        else
         {
           for(int i=0;i<n;i+=2)
            {
             int temp=arr[i];
             arr[i]=arr[i+1];
             arr[i+1]=temp;
            }
         }
        
        if(n%2==0)
        {
        for(int i=0;i<n;i++)
         {
          System.out.print(arr[i]+" ");
         }
        } 
      }
}