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;
const double EPS = 1e-9;
const int INF = 1 << 28;
const long long INFL = 1LL << 62;
string res[] = {"NO", "YES"};
int main() {
  int n;
  cin >> n;
  if (n % 2 != 0) {
    cout << -1 << endl;
  } else {
    vector<int> v(n);
    for (int i = 0; i < n; ++i) v[i] = i + 1;
    for (int i = 0; i < n - 1; i += 2) swap(v[i], v[i + 1]);
    for (int i = 0; i < n; ++i) cout << v[i] << " ";
    cout << endl;
  }
}