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:
def swap(arr,i,j):
    arr[i],arr[j]=arr[j],arr[i]
n=int(input())
ll=[]
for i in range(1,n+1):
    ll.append(i)
i=0
j=1
a=[k for k in ll]
while i< n-1 and j<n:
    swap(ll, i, j)
    i+=2
    j+=2
flag=1
for i in range(n):
    if (i+1)==ll[i]:
        flag=0
        break
if flag==1:
    print(*ll)
else:
    print(-1)