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.*;

 // Compiler version JDK 11.0.2

 public class Dcoder
 {
   public static void main(String args[])
   { 
    Scanner sc=new Scanner(System.in);
    List<Integer> l=new ArrayList<>();
    List<Integer> l1=new ArrayList<>();
    int n=sc.nextInt();
    if(n % 2 != 0){
      System. out. println("-1");
    }else{
      int i=1;
      int m=n;
      while(n-- > 0){
        if(i% 2 != 0){
          l. add(i);
        }else{
          l1. add(i);
        }
        i++;
      }
     // System. out. println(l);
      //System. out. println(l1);
      int k=0;
      int u=0;
      for(int j=1; j<=m; j++){
       if(j% 2 != 0){
          System.out.print(l1. get(k)+" ");
          k++;
        }else{
          System.out.print(l. get(u)+" ");
          u++;
        }
      }
    }
   }
 }