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 {
    static long gcd( long a, long b )    {
        if ( a==0 ) return b;
        return gcd( b%a, a );
    }

    public static void main(String[] args)  {
        // write your code here
        Scanner sc= new Scanner(System.in);
        int n= sc.nextInt();
        if(n%2!=0) {System.out.println("-1");return;}
        else{
            for (int i = 1; i <=n ; i++) {
                System.out.print((i%2!=0?(i+1):(i-1) )+" ");
            }
        }
    }
}