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;

/**
 *
 * @author farah
 */
public class AhmadAli {

    /**
     * @param args the command line arguments
     */
    public static void light(){
        Scanner sc= new Scanner(System.in);
        int arr[][]=new int[3][3];
        for(int i=0 ; i<3 ; i++)
            for(int j=0 ; j<3 ; j++)
                arr[i][j]=sc.nextInt();
        
        int sumArr[][]=new int[3][3];
        for(int i=0 ; i<3 ; i++){
            for(int j=0 ; j<3 ; j++){
                sumArr[i][j]=arr[i][j];
                for(int k=0 ; k<3 ; k++){
                    
                    if(j!=k)
                        sumArr[i][j]+=arr[i][k];

                    if(i!=k)
                        sumArr[i][j]+=arr[k][j];

                }
            }
        }
        for(int i=0 ; i<3 ; i++){
            for(int j=0 ; j<3 ; j++)
                System.out.print(sumArr[i][j]+" ");
            System.out.println("");
        }
        System.out.println(",,,,,,,,,,,,,,,,,,,,,");
        for(int i=0 ; i<3 ; i++)
            for(int j=0 ; j<3 ; j++)
                if(sumArr[i][j]%2==0)
                    sumArr[i][j]=1;
                else
                    sumArr[i][j]=0;
            
        
        for(int i=0 ; i<3 ; i++){
            for(int j=0 ; j<3 ; j++)
                System.out.print(sumArr[i][j]);
            System.out.println("");
        }
           
    }
    public static void main(String[] args) {
        Scanner sc= new Scanner(System.in);
        int n=sc.nextInt();
        if(n%2==1)System.out.println("-1");
        else{
            int i=1;
            while(i<n){
                System.out.print(i+1+" "+i+" ");
                i+=2;
            }
        }
    }
    
}