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