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())
if n==1:
    print(-1)
else:
    if n%2==0:
        li =[i for i in range(1,n+1)]
        for j in range(0,len(li),2):
            li[j],li[j+1]=li[j+1],li[j]
        print(*li)
    else:
        print(-1)
        """
        li = [i for i in range(1, n + 1)]
        c = 1
        for j in range(0, len(li)//2, 1):
            li[j], li[len(li) - c] = li[len(li) - c], li[j]
            c += 1
        li[len(li)//2],li[len(li)-1]=li[len(li)-1],li[len(li)//2]
        print(*li)
        """