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 CPP):

Solution:
#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(0);
  ios::sync_with_stdio(0);
  cin.tie(0), cout.tie(0);
  string s, c;
  long long y, x, n, mx = -1, sum = 0, arr[1000] = {}, zero = 0, l = 0, z = 0,
                     a, b, r = 0, cont = 0;
  map<int, int> mp;
  cin >> x;
  if (x % 2 != 0 || x == 0) {
    cout << "-1";
    return 0;
  }
  for (int k = 1; k <= x; k += 2) {
    cout << k + 1 << " " << k << " ";
  }
  return 0;
}