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 PYTHON):

Solution:
#!/usr/bin/env python
from sys import stdin
n = int(stdin.readline())
print " ".join(str(r) for r in xrange(n, 0, -1)) if ~n&1 else -1

#Reason why we don't print permutations for odd values is not because they
#do not exist (They do exist!) but because of one of the conditions. This 
#condition being Ppi or in more understandable terms P[P[i]] = i.
#So if you have the number 3 and the permutation, the possible permutations
#you can have to satisfy the second condition are:

#A = [ 3 1 2 ] or B = [ 2 3 1 ]

# if we try to apply the first condition to any of the sets, we can see that
#A[A[2]] = A[1] != 2
#B[B[2]] = B[3] != 2

#And as soon as one of these conditions fail, there cannot be a perfect permutation