human
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 
"""
A
assistant
#Here is Python code to print any perfect permutation of size n for the given n.
uthor : Aman Thakur
mantra: chor kya hi kar sakte hai!!
"""
import math

class Solution:
    def solution(self):
        n = int(input())

        num = list(str(i) for i in range(n, 0, -1))
        if n % 2 != 0:
            print(-1)
        else:
            print(' '.join(num))

if __name__ == '__main__':
    ob = Solution()
    ob.solution()