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.*;
public class one
{
public static void main(String args[])
{
Scanner ss=new Scanner(System.in);
int n=ss.nextInt();

if(n%2==0)
{
int a[]=new int[n];
for(int i=0;i<n;i++)
{
a[i]=i+1;
}
int i=0, j=n-1;
while(i<j)
{
int t=a[i];
a[i]=a[j];
a[j]=t;
i++;
j--;
}
for(i=0;i<n;i++)
{
System.out.print(a[i]+" ");
}

}
else
System.out.println("-1");
}
}