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 static java.lang.Math.ceil;
import static java.lang.Math.sqrt;
 import java.util.Scanner;
 
    public class prob2 {
        public static void main(String[] args) {
            Scanner input = new Scanner(System.in);
            long t;
               long n,a,b,x,i,ev=0,cnt=0,sum1=0,sum2=0,m;
                n=input.nextInt();
                for(i=1;i<=n;i++){
                if(n%2==0){
                     sum1=n-i+1;
                    System.out.print(sum1+" "); }
         
                   
	 
}
                if(n%2!=0){
                        System.out.println(-1); }
                
               
              
                 
            }
    }