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 A2j {
 
    public static void main(String[] args) {
      
         Scanner sc=new Scanner(System.in);
         int in=sc.nextInt();
         if(in==1||in==0||in%2!=0){System.out.println("-1");}
         
         else if(in%2==0){
            for(int i=2;i<=in;i+=2){
              for(int j=i;j>=i-1;j--){
                  System.out.print(j+" ");
            
            }
            
            }
        
        
        }
       
}
  
    }