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) or (n%2!=0):
    print("-1")
else:
    l=[(x+1) for x in range(n)]
    i=0
    if(n%2==0):
    	while(i<len(l)):
        	l[i],l[i+1]=l[i+1],l[i]
        	i=i+2
    #if(n%2!=0):
    	#while(i<len(l)-1):
    	#	l[i],l[i+1]=l[i+1],l[i]
    	#	i+=1

    #print(l)
    #print(' '.join (d) for d in l)
    print(*l,sep=' ')