A permutation is a sequence of integers p1, p2, ..., p**n, consisting of n distinct positive integers, each of them doesn't exceed n. Let's denote the i-th element of permutation p as p**i. We'll call number n the size of permutation p1, p2, ..., p**n.

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 p**i ≠ 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, ..., p**n — permutation p, that is perfect. Separate printed numbers by whitespaces.

Samples

1

-1

2

2 1 

4

2 1 4 3