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:
# import sys
# sys.stdin = open('input.txt', 'r') 
# sys.stdout = open('output.txt', 'w')

def solve(n):
	if n & 1:
		print('-1')
		return
	result = []

	for i in range(1, n+1):
		result.append(i)
	
	for i in range(1, n, 2):
		result[i], result[i-1] = result[i-1], result[i]
	print(*result)

n = int(input())
# print(n)
# arr = list(map(int, input().strip().split()))
solve(n)
# print(*result)