#include <cstdio>
#include <vector>
#include <algorithm>

#define PB push_back

using namespace std;

typedef vector < int > vi;

const int OFF = (1 << 10) + 1;
const int N = 50;

int n, T[2 * OFF], pos[2 * OFF], list[2 * OFF];
vector < int > v[2 * OFF];

bool inter(vi &A, vi &B) {
	int i = 0, j = 0;
	while(i < (int)A.size() && j < (int)B.size()) {
		if(A[i] == B[j]) return true;
		else if(A[i] < B[j]) i++;
		else j++;
	}
	return false;
}

int ban[N], cur_sub[2 * OFF], list_ind[2 * OFF];
int rezo[2 * OFF], off;
vector < int > makni;
int kolko_rezo, ans;

void brute(int ind) {
	if(ind == (int)makni.size()) {
		ans = min(ans, kolko_rezo);
		return;
	}
	int x = makni[ind];
	//printf("ind = %d x = %d kolko_rezo = %d\n", ind, x, kolko_rezo);
	int lijevo = cur_sub[2 * x];
	int desno = cur_sub[2 * x + 1];
	bool dobar = true;
	//printf("L = %d R = %d\n", lijevo, desno);
	for(;lijevo; lijevo -= lijevo & -lijevo) {
		if(ban[__lg(lijevo & -lijevo)] & desno) {
			dobar = false; break;
		}
	}
	//printf("dobar = %d ban %d %d\n", dobar, ban[0], ban[1]);
	if(dobar) {
		brute(ind + 1);
	} else if(kolko_rezo < n - __lg(x)){
		int tata = x;
		while(tata > 1 && !rezo[tata]) tata >>= 1;
		kolko_rezo++;
		rezo[2 * x] = 1;
		for(int y = x;y >= tata;y >>= 1)
			cur_sub[y] ^= cur_sub[2 * x];
		brute(ind + 1);
		rezo[2 * x] = 0;
		rezo[2 * x + 1] = 1;
		for(int y = x;y >= tata;y >>= 1)
			cur_sub[y] ^= cur_sub[2 * x] ^ cur_sub[2 * x + 1];
		brute(ind + 1);
		for(int y = x;y >= tata;y >>= 1)
			cur_sub[y] ^= cur_sub[2 * x + 1];
		rezo[2 * x + 1] = 0;
		kolko_rezo--;
	}
}

void ocisti() {
	
	
	for(int i = 0;i <= 2 * off;i++) {
		v[i].clear(); 
		cur_sub[i] = 0; list[i] = 0; pos[i] = 0;
		list_ind[i] = 0; rezo[i] = 0; T[i] = 0;
	}
	for(int i = 0;i < N;i++) {
		ban[i] = 0;
	}
	
	makni.clear();
	
}

void solve() {
	scanf("%d", &n);
	off = (1 << n);
	T[1] = 0;
	for(int i = 2;i < 2 * off;i++) {
		scanf("%d", T + i);
	}
	for(int i = 2;i < off;i++) T[2 * i] += T[i], T[2 * i + 1] += T[i];
	for(int i = off;i < 2 * off;i++) {
		v[i].PB(T[i]);
	}
	for(int i = off - 1;i >= 1;i--) {
		for(int x : v[2 * i]) v[i].PB(x);
		for(int x : v[2 * i + 1]) v[i].PB(x);
		sort(v[i].begin(), v[i].end());
		v[i].erase(unique(v[i].begin(), v[i].end()), v[i].end());
		v[i].shrink_to_fit();
		pos[i] = (int)v[i].size() < (1 << (n - __lg(i)));
	}
	//printf("kuku %d\n", (int)v[1].size());
	if(!pos[1]) {
		printf("0\n");
		ocisti();
		return;
	}
	vector < int > svi;
	int list_cnt = 0;
	for(int i = 1;i < 2 * off;i++) {
		//printf("pos[ %d ] = %d\n", i, pos[i]);
		if(i == 1 || pos[i >> 1]) {
			if(!pos[i]) {
				//printf("list %d %d\n", i, list_cnt);
				list[i] = 1, list_ind[i] = list_cnt++;
			}
			else makni.PB(i);
			svi.PB(i);
		}
	}
	reverse(makni.begin(), makni.end());
	//printf("list_cnt = %d\n", list_cnt);
	if((int)svi.size() > 4 * n) {
		printf("-1\n");
		ocisti();
		return;
	}
	int m = (int)svi.size();
	for(int i = 0;i < m;i++) {
		if(!list[svi[i]]) continue;
		for(int j = i + 1;j < m;j++) {
			if(!list[svi[j]]) continue;
			if(inter(v[svi[i]], v[svi[j]])) {
				//printf("banana %d %d\n", list_ind[svi[i]], list_ind[svi[j]]);
				ban[list_ind[svi[i]]] |= (1 << list_ind[svi[j]]);
				ban[list_ind[svi[j]]] |= (1 << list_ind[svi[i]]);
			}
		}
	}
	
	
	for(int i = 2 * off - 1;i >= 1;i--) {
		if(list[i]) {
			cur_sub[i] = 1 << list_ind[i];
		} else if(pos[i]) {
			cur_sub[i] = cur_sub[2 * i] | cur_sub[2 * i + 1];
		}
	}
	
	ans = 100;
	kolko_rezo = 0;
	brute(0);
	
	if(ans == 100) {
		printf("-1\n");
	} else {
		printf("%d\n", ans);
	}
	
	ocisti();
}

int main() {
	int T; scanf("%d", &T);
	for(;T--;) {
		solve();
	}
	return 0;
}