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:
"""
Let p be a permutation such that for all i p[p[i]] = i. Let p[i] = j, then p[j] = i, which implies a
transposition. So p is product of transpositions, hence if n is odd then no transposition exists.
"""

def find_transposition(n):
    
    if n % 2 == 1:
        return -1
    
    result = [i + 1 for i in xrange(n)]
    for i in xrange(0, n, 2):
        temp = result[i]
        result[i] = result[i + 1]
        result[i + 1] = temp
    
    return " ".join(map(str, result))
    
n = input()
print find_transposition(n)