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.Scanner;

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