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 Test{
    
   public static void main(String args[]){
       Scanner sc = new Scanner(System.in);
       int n = sc.nextInt();
       if(n%2!=0)System.out.println(-1);
       else{
           int[] arr = foo1(n);
           for (int i : arr) System.out.print(i + " ");
       }
   }
   public static int[] foo1(int n){
       int []arr = new int[n];
       for(int i =0; i<n; i++) arr[i]=i+1;
       return foo2(arr,n);
   }
   public static int[] foo2(int[] arr,int n){
       int temp;
       for(int i = 0; i < n; i++){
           temp = arr[i];
           arr[i] = arr[i+1];
           arr[i+1] = temp;
           i++;
       }
       return arr;
   }
}