#include <bits/stdc++.h>
using namespace std;
int n;
void solve() {
  cin >> n;
  cout << 1 << ' ' << n - 1 << endl;
  cout << 1 << endl;
  for (int i = 2; i <= n; i++) {
    cout << i << ' ';
  }
  cout << endl;
  int mx;
  cin >> mx;
  int l = 1, r = n;
  while (r - l > 1) {
    int md = (l + r) / 2;
    cout << 1 << ' ' << md - 1 << endl;
    cout << 1 << endl;
    for (int i = 2; i <= md; i++) {
      cout << i << ' ';
    }
    cout << endl;
    int cur;
    cin >> cur;
    if (cur == mx) {
      r = md;
    } else {
      l = md;
    }
  }
  cout << 1 << ' ' << n - 1 << endl;
  cout << r << endl;
  for (int i = 1; i <= n; i++) {
    if (i != r) {
      cout << i << ' ';
    }
  }
  cout << endl;
  int res;
  cin >> res;
  cout << -1 << ' ' << res << endl;
}
int main() {
  cin.tie(nullptr);
  cout.tie(nullptr);
  ios::sync_with_stdio(false);
  int t;
  cin >> t;
  for (int i = 0; i < t; i++) {
    solve();
  }
}
