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:
import copy
import math
import sys

def solve(n):
    if n%2== 1:
        return -1
    else:
        ret=range(1, n+1)
        half = n/2
        for i in range(half):
            ret[i] += half
            ret[i+half] -= half
        return " ".join(map(str, ret))



if __name__ == '__main__':

    try:
        str_in = __file__[:-2]+"in"
        f_in = open(str_in)
        f_out = open(str_in.rstrip('.in') + '.out', 'w')
        FLAG_LOCAL = True
    except:
        FLAG_LOCAL = False
        f_in = sys.stdin


    n = int(f_in.next())
    output = str(solve(n))

    print output,

    if FLAG_LOCAL:
        f_out.write(output)
        f_in.close()
        f_out.close()