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:
"""CODE FOR CODEFORCES 140 DIV II PROB A"""
n = int(raw_input())

perm = []
for x in range(1,n+1):
    perm.append(x)

def main():
    if n % 2 != 0: return -1
    else:
        for k in range(1,n,2):
            tmp = int(perm[k])
            perm[k] = perm[k-1]
            perm[k-1] = tmp
        return perm


newPerm = main()
if newPerm == -1: print -1
else:
    res = ''
    for x in newPerm:
        res = res + str(x) + " "
    print res

"""
1  2  3  4  5  6
0  1  2  3  4  5
2  1  4  3  6  5
"""