#include <bits/stdc++.h>
using namespace std;
int main() {
  int t;
  cin >> t;
  for (int i = 0; i < t; i++) {
    int n;
    scanf("%d", &n);
    int lower = 2;
    int upper = n + 1;
    int dprev = 0;
    int first = true;
    while (true) {
      if (upper <= lower + 1) break;
      int num = upper - lower;
      int s = first ? num : num / 2;
      int d1;
      cout << "1 " << s << " 1 ";
      for (int j = lower; j < lower + s; j++) {
        cout << j << " ";
      }
      cout << endl;
      cout.flush();
      cin >> d1;
      if (first) {
        first = false;
        dprev = d1;
        continue;
      }
      if (d1 == dprev) {
        dprev = d1;
        upper = lower + s;
      } else
        lower = lower + s;
    }
    cout << "1 " << (n - 1) << " " << lower << " ";
    for (int j = 1; j <= n; j++) {
      if (j != lower) cout << j << " ";
    }
    cout << endl;
    cout.flush();
    int d;
    cin >> d;
    cout << "-1 " << d << endl;
    cout.flush();
  }
}
