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 .

输入描述:

A single line contains a single integer n (1 ≤ n ≤ 100) — the permutation size.

输出描述:

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.