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
import math
from statistics import mean

input = sys.stdin.readline


############ ---- Input Functions ---- ############
def inp():
    return (int (input ()))


def inlt():
    return (list (map (int, input ().split ())))


def insr():
    s = input()
    return (list (s[:len (s) - 1]))


def invr():
    return (map (int, input ().split ()))


n = inp()
if n % 2 != 0:
    print(-1)
else:
    for k in range(1, n+1):
        if k % 2 != 0:
            print(k+1, end=" ")
        else:
            print(k-1,end =" ")