#include <bits/stdc++.h>
using namespace std;
int TN = 1;
void ans() {
  int n, c, s;
  cin >> n;
  vector<int> a, b;
  for (int i = 0; i < n; i++) {
    int x;
    cin >> x;
    if (x % 2 == 0) {
      a.push_back(i);
    }
    if (x % 2 == 1) {
      b.push_back(i);
    }
  }
  c = b.size();
  s = a.size();
  if (c % 2 == 1) {
    c--;
  }
  if (s % 2 == 1 && s != 1) {
    s--;
  }
  if (b.size() == 1 && a.size() == 0) {
    cout << -1;
  } else {
    cout << s + c << endl;
    for (int i = 0; i < c; i++) {
      cout << b[i] + 1 << " ";
    }
    for (int i = 0; i < s; i++) {
      cout << a[i] + 1 << " ";
    }
  }
  cout << endl;
}
int main() {
  cin >> TN;
  for (int i = 0; i < TN; i++) {
    ans();
  }
  return 0;
}
