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:
while True:
	try:
		class Permutation:
			def __init__(self):
				self.p = [ ]
				self.n  = 0
				
			def inputt(self):
				self.n = int(input())
				
			def solve(self):
				if self.n%2 == 1:
					print(-1)
				else:
					yn = False
					for i in range(self.n):
						if yn:
							self.p.append(i);yn = False
						else:
							self.p.append(i+2);yn = True
					print(*self.p)
						
				
		if __name__=="__main__":
			c1 = Permutation()
			c1.inputt()
			c1.solve()
			
	except EOFError:
		break