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

def input():    return sys.stdin.readline().strip()
def iinput():   return int(input())
def rinput():   return map(int, sys.stdin.readline().strip().split()) 
def get_list(): return list(map(int, sys.stdin.readline().strip().split())) 


n=iinput()
a=[]
if(n%2!=0):
    print(-1)
else:
    for i in range(1,n+1):
        a.append(i)
    #print(a)
    i=0
    while(i<n):
        a[i], a[i+1] = a[i+1], a[i]
        i+=2
    print(*a)