#include <bits/stdc++.h>
using namespace std;
using namespace std;
template <typename Arg1>
void __f(const char* name, Arg1&& arg1) {
  cerr << name << " : " << arg1 << '\n';
}
template <typename Arg1, typename... Args>
void __f(const char* names, Arg1&& arg1, Args&&... args) {
  const char* comma = strchr(names + 1, ',');
  cerr.write(names, comma - names) << " : " << arg1 << " | ";
  __f(comma + 1, args...);
}
long long int gcd(long long int a, long long int b) {
  if (a < b)
    return gcd(b, a);
  else if (b == 0)
    return a;
  else
    return gcd(b, a % b);
}
long long int isPrime(long long int n) {
  long long int p = (long long int)sqrt(n);
  for (int i = (2); i <= (p); i += (1))
    if (n % i == 0) return 0;
  return 1;
}
long long int pow(long long int b, long long int e) {
  if (e == 0)
    return 1;
  else if (e % 2 == 0) {
    long long int a = pow(b, e / 2);
    return a * a;
  } else {
    long long int a = pow(b, e / 2);
    return b * a * a;
  }
}
long long int powm(long long int x, long long int y,
                   long long int m = 1000000007) {
  x = x % m;
  long long int res = 1;
  while (y) {
    if (y & 1) res = res * x;
    res %= m;
    y = y >> 1;
    x = x * x;
    x %= m;
  }
  return res;
}
long long int modInverse(long long int a, long long int m) {
  return powm(a, m - 2, m);
}
void solve() {
  int n, maxd;
  cin >> n;
  cout << "1 " << n - 1 << " ";
  for (int i = (1); i <= (n); i += (1)) cout << i << " ";
  cout << '\n';
  cout.flush();
  cin >> maxd;
  int l = 1, r = n - 1;
  while (l <= r) {
    int mid = l + ((r - l) / 2);
    int ans;
    cout << "1 " << mid << " ";
    for (int i = (1); i <= (1 + mid); i += (1)) cout << i << " ";
    cout << '\n';
    cout.flush();
    cin >> ans;
    if (ans < maxd)
      l = mid + 1;
    else
      r = mid - 1;
  }
  int ans;
  cout << "1 " << n - 1 << " " << l + 1 << " ";
  for (int i = (1); i <= (n); i += (1))
    if (i != l + 1) cout << i << " ";
  cout << '\n';
  cout.flush();
  cin >> ans;
  cout << "-1 " << ans << '\n';
  cout.flush();
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  ;
  int T;
  cin >> T;
  while (T--) {
    solve();
  }
  return 0;
}
