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.InputStreamReader;
import java.io.BufferedReader;
import java.io.IOException;


/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 */
public class Main{
    static int arr[];
    public static void main(String[] args)throws IOException {
       
       BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
       
        int t = Integer.parseInt(in.readLine());
      arr =new int [t];
      for (int j =0 ; j < t;j++)
      {
          arr[j]=j+1;
      }
      if(t%2==0)
      {
        for ( int i = 0 ; i < t-1 ; i +=2 )
        {
            swap(i,i+1);
        }
        
        for (int row : arr)
                System.out.print(row+" ");
      }
      else System.out.println(-1);
        }
        
    static void swap(int i , int i1)
    {
        int temp = arr[i];
        arr[i]=arr[i1];
        arr[i1]=temp;
    }
}