#include <bits/stdc++.h>
using namespace std;
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int tt;
  cin >> tt;
  while (tt--) {
    int n;
    cin >> n;
    cout << 1 << ' ' << n - 1;
    cout << ' ' << 1;
    for (int i = 2; i <= n; i++) {
      cout << ' ' << i;
      if (i == n) cout << endl;
    }
    int ans = 0;
    cin >> ans;
    int low = 2, high = n;
    for (int i = 0; i < 7; i++) {
      int mid = (low + high) >> 1;
      cout << 1 << ' ' << mid - low + 1;
      cout << ' ' << 1;
      for (int i = low; i <= mid; i++) {
        cout << ' ' << i;
        if (i == mid) cout << endl;
      }
      int t;
      cin >> t;
      if (t >= ans)
        high = mid;
      else
        low = mid + 1;
    }
    ans = (low + high) >> 1;
    cout << 1 << ' ' << n - 1;
    cout << ' ' << ans;
    for (int i = 1; i <= n; i++) {
      if (i != ans) cout << ' ' << i;
    }
    cout << endl;
    cin >> ans;
    cout << -1 << ' ' << ans << endl;
  }
  return 0;
}
