#include <bits/stdc++.h>
using namespace std;
void solve() {
  int n;
  cin >> n;
  cout << "1 " << n - 1 << " ";
  for (int i = 1; i <= n; i++) {
    cout << i << " ";
  }
  cout << endl;
  cout.flush();
  int dd;
  cin >> dd;
  int l = 2;
  int r = n;
  while (l != r) {
    int mid = l + r;
    mid /= 2;
    cout << mid - l + 1 << " " << 1 << " ";
    for (int i = l; i <= mid; i++) {
      cout << i << " ";
    }
    cout << "1 " << endl;
    cout.flush();
    int tt;
    cin >> tt;
    if (dd == tt) {
      r = mid;
    } else {
      l = mid + 1;
    }
  }
  cout << "1 " << n - 1 << " ";
  cout << l << " ";
  for (int i = 1; i <= n; i++) {
    if (i != l) {
      cout << i << " ";
    }
  }
  cout << endl;
  cout.flush();
  int ans;
  cin >> ans;
  cout << "-1 " << ans << endl;
}
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  ;
  int t;
  cin >> t;
  for (int i = 1; i <= t; i++) {
    solve();
  }
  return 0;
}
