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 PerfectPermutation {
    static void permute(int n){
        int arr[] = new int[n];
        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]+" ");
    }
    public static void main(String args[]){
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        if(n%2==0)
            permute(n);
        else
            System.out.println("-1");
        sc.close();
    }
}