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 sys import stdin,stdout
from math import gcd,sqrt,floor,ceil
import random
# Fast I/O
input = stdin.readline
#print = stdout.write

def list_inp(x):return list(map(x,input().split()))
def map_inp(x):return map(x,input().split())

def lcm(a,b): return (a*b)//gcd(a,b)



n = int(input())

if n%2:
    print(-1)
else:
    for i in range(n,0,-1):
        print(i,end =' ')