#include <bits/stdc++.h>
using namespace std;
bool prime[101];
void SieveOfEratosthenes(int n) {
  memset(prime, true, sizeof(prime));
  for (int p = 2; p * p <= n; p++) {
    if (prime[p] == true) {
      for (int i = p * p; i <= n; i += p) prime[i] = false;
    }
  }
}
int main() {
  long long n, m;
  cin >> n;
  long long c[n + 1];
  if (n % 2 != 0) {
    cout << -1;
    return 0;
  }
  for (long long i = 1; i <= n; i++) {
    c[i] = i;
  }
  for (long long i = 1; i <= n; i += 2) {
    swap(c[i], c[i + 1]);
  }
  for (long long i = 1; i <= n; i++) {
    cout << c[i] << " ";
  }
}

### Prompt

Generate a cpp solution to the following 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 

### Response

```cpp
#include <bits/stdc++.h>
using namespace std;
bool prime[101];
void SieveOfEratosthenes(int n) {
  memset(prime, true, sizeof(prime));
  for (int p = 2; p * p <= n; p++) {
    if (prime[p] == true) {
      for (int i = p * p; i <= n; i += p) prime[i] = false;
    }
  }
}
int main() {
  long long n, m;
  cin >> n;
  long long c[n + 1];
  if (n % 2 != 0) {
    cout << -1;
    return 0;
  }
  for (long long i = 1; i <= n; i++) {
    c[i] = i;
  }
  for (long long i = 1; i <= n; i += 2) {
    swap(c[i], c[i + 1]);
  }
  for (long long i = 1; i <= n; i++) {
    cout << c[i] << " ";
  }
}

```