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:
from itertools import permutations
def solve(n):
	if(n%2 != 0):
		return -1
	a = []
	for i in range(1, n+1):
		a.append(i)
	for i in range(0, n, 2):
		a[i], a[i+1] = a[i+1], a[i]
	return a


n = int(input())
x = solve(n)
if(x == -1):
	print(x)
else:
	for i in x:
		print(i, end = " ")
'''
x = []
for i in range(1, n+1):
	x.append(i)
perms = permutations(x)
ans = []
for perm in perms:
	f = 1
	for x in range(len(perm)):
		if(perm[perm[x]-1] != x+1 or perm[x] == x+1):
			f = 0
			break
	if(f):
		ans = perm
		break
if(len(ans) == 0):
	print(-1)
else:
	for i in ans:
		print(i, end = " ")
'''