A permutation is a sequence of integers p_1, p_2, ..., 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 p_1, p_2, ..., 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 p_{p}_{i} = 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, p_1, p_2, ..., p_{n} — 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