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