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 PYTHON3):

Solution:
def int_lst_input():
    return [int(val) for val in input().split(' ')]

def int_input():
    return int(input())

def print_lst(lst):
    print(' '.join([str(val) for val in lst]))

def solve():
    n = int_input()

    res = [0 for _ in range(n)]

    if n % 2 == 1:
        print(-1)
        return
    else:
        for i in range(0, n, 2):
            res[i] = i + 1
            res[i+1] = i + 2
            res[i], res[i + 1] = res[i + 1], res[i]

    print_lst(res)

if __name__ == '__main__':
    solve()