newCode.cpp

//
// Created by Ashish Raj Singh on 26/09/26.
//

#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
#include <map>
#include <set>
#include <queue>
#include <stack>
#include <cmath>

using namespace std;

// --- Macros & Type Aliases ---
using ll = long long;
using ld = long double;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
using vi = vector<int>;
using vll = vector<ll>;

#define fast_io ios_base::sync_with_stdio(false); cin.tie(nullptr); cout.tie(nullptr);
#define pb push_back
#define all(x) (x).begin(), (x).end()
#define sz(x) (int)(x).size()

// --- Debugging (Only active on local machine) ---
#ifndef ONLINE_JUDGE
#define debug(x) cerr << #x << " = " << x << endl;
#else
#define debug(x)
#endif

// --- Core Logic ---
void solve() {
	int n;
	cin>>n;
	vector<pair<int, int>> v(n);
	for(int i=0;i<n;i++) {
		int a;
		cin>>a;
		v[i]={a,i};
	}

	sort(all(v));

	vector<ll> prefix(n);
	prefix[0]=v[0].first;
	for(int i=1;i<n;i++) {
		prefix[i]=prefix[i-1]+v[i].first;
	}


	int l =0, r = n-1;
	while (l<=r) {
		if (l == r) {
			cout<<"! "<<v[l].second+1<<endl;
			return;
		}
		int m = l + (r-l)/2;


		long long sum;
		if (l == 0) {
			sum = prefix[m];
		} else {
			sum = prefix[m] - prefix[l-1];
		}

		cout<<"? "<<m-l+1<<" ";
		for (int i =l; i<=m; i++) cout<<v[i].second+1<<" ";
		cout<<endl;
		int x;
		cin>>x;

		if (x > sum) {
			r = m;
		} else {
			l = m+1;
		}


	}

}

int main() {
	fast_io;

	int t = 1;
	cin >> t; // Comment this out if the problem has only one test case
	while (t--) {
		solve();
	}

	return 0;
}