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;
bool isPrime(int n) {
  for (int i = 2; i * i <= n; i++) {
    if (n % i == 0) return false;
  }
  return true;
}
int nextPrime(int n) {
  if (n == 2) return 3;
  int x = n + 1;
  while (true) {
    if (isPrime(x)) return x;
    x++;
  }
}
int main() {
  int n;
  cin >> n;
  vector<int> p;
  if (n % 2 != 0)
    cout << -1;
  else {
    for (int i = 0; i < n; i++) {
      p.push_back(i + 1);
    }
    for (int i = 0; i < n - 1;) {
      int temp = p[i + 1];
      p[i + 1] = p[i];
      p[i] = temp;
      cout << p[i] << " " << p[i + 1] << " ";
      i += 2;
    }
  }
  return 0;
}