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:
n = int(input())
l1,l2 = [],[]
t = 0
if n%2!=0:
	print(-1)
else:
	for x in range(1,n+1):
		if x%2==0:
			l2.append(x)
		else:
			l1.append(x)
	for x in range(n):
		if t==0:
			print(l2[0],end=" ")
			t=1
			l2.remove(l2[0])
		else:
			print(l1[0],end=" ")
			t=0
			l1.remove(l1[0])