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 perfectPermutation {
    public static String perfectPermutation(int n){
        if(n%2 ==1){
            System.out.print(-1);
            return "-1";
        }
        else{
            String result = "";
            for(int i = 1; i<=n; i++){
                if(i%2==1){
                    result = result+(i+1)+" ";
                }
                else{
                    result = result+(i-1)+" ";
                }
            }
            result = result.substring(0, result.length()-1);
            System.out.print(result);
            return result;
        }
    }
    
    public static boolean isPerfect(String per){
        if(per.equals("-1")){
            return false;
        }
        else{
            String [] array = per.split(" ");
            int [] numbers = new int [array.length+1];
            for(int i =0; i<array.length; i++){
                numbers[i+1] = Integer.parseInt(array[i]);
            }
            for(int i =1; i<numbers.length; i++){
                if(numbers[i]==i){
                    return false;
                }
                if(numbers[numbers[i]]!=i)
                    return false;
            }
            return true;
        }
        
    }
    
    public static void main(String[]args){
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        /*for(int i =1; i<15; i++){
            //System.out.print(i+" ");
            String per = perfectPermutation(i);
            //System.out.println(" "+ isPerfect(per));
        }*/
        String per = perfectPermutation(n);
        
    }

}