#include <bits/stdc++.h>
using namespace std;
int main() {
  int t;
  cin >> t;
  while (t--) {
    int n;
    cin >> n;
    int a[n], odd = 0, evenindex;
    for (int i = 0; i < n; i++) {
      cin >> a[i];
      if (a[i] % 2 == 1) odd++;
      if (a[i] % 2 == 0) evenindex = i + 1;
    }
    if (n == 1 && a[0] % 2 == 1)
      cout << -1 << endl;
    else if (odd == n)
      cout << "2\n1 2\n";
    else
      cout << "1\n" << evenindex << endl;
  }
  return 0;
}
