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:
#!/usr/bin/env python
# coding: utf-8

# In[204]:


# # n = int(input())
# # line = list(map(int, input().split()))
# # line = list(str(input()))


# In[669]:


n = int(input())


# In[676]:


seq = ''

if n == 1 or n%2 != 0:
    print('-1')
else:
    for i in range(1, n + 1):
        if i%2 != 0:
            seq += str(i + 1) + " "
        else:
            seq += str(i - 1) + " "

print(seq[:-1])


# In[ ]: