#ifdef LOCAL
#define _GLIBCXX_DEBUG
#endif
#include <bits/stdc++.h>

using namespace std;
#define int long long
const int p=998244353;
int po(int a,int b) {if(b==0) return 1; if(b==1) return a; if(b%2==0) {int u=po(a,b/2);return (u*1LL*u)%p;} else {int u=po(a,b-1);return (a*1LL*u)%p;}}
int inv(int x) {return po(x,p-2);}
mt19937 rnd;
#define app push_back
#define all(x) (x).begin(),(x).end()
#ifdef LOCAL
#define debug(...) [](auto...a){ ((cout << a << ' '), ...) << endl;}(#__VA_ARGS__, ":", __VA_ARGS__)
#define debugv(v) do {cout<< #v <<" : {"; for(int izxc=0;izxc<v.size();++izxc) {cout << v[izxc];if(izxc+1!=v.size()) cout << ","; }cout <<"}"<< endl;} while(0)
#else
#define debug(...)
#define debugv(v)
#endif
#define lob(a,x) lower_bound(all(a),x)
#define upb(a,x) upper_bound(all(a),x)
template<typename T>
using pqg = priority_queue<T,vector<T>, greater<>>;
int32_t main()
{
    ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
    int N = 10;
    vector<vector<int>> lca(1 << (N + 1), vector<int>(1 << (N + 1)));
    for (int x = 1; x < lca.size(); ++x) {
        for (int y = 1; y < lca.size(); ++y) {
            int a = x, b = y;
            while (a != b) {
                if (a > b) swap(a, b); // a < b
                b /= 2;
            }
            lca[x][y] = a;
        }
    }
    int t;cin>>t;
    while (t--) {
        int n;
        cin >> n;
        vector<int> a(1 << (n + 1));
        for (int i = 2; i < a.size(); ++i) cin >> a[i];
        vector<int> sum(1 << (n + 1));
        for (int i = 1; i < (1 << n); ++i) {
            sum[2 * i] = sum[i] + a[2 * i];
            sum[2 * i + 1] = sum[i] + a[2 * i + 1];
        }
        vector<int> sums = sum;
        sort(all(sums), [](int x, int y){ return x < y; });
        sums.erase(unique(all(sums)), sums.end());
        for (auto &s : sum) s = lower_bound(all(sums), s) - sums.begin();
        vector<vector<int>> below(1 << (n + 1));
        for (int i = 1 << n; i < (1 << (n + 1)); ++i) {
            below[i] = {sum[i]};
        }
        int ans = n + 1, cur = 0;
        auto first_unset = [&](int bit) {
            while (cur & (1 << bit)) {
                bit++;
            }
            return bit;
        };
        auto go = [&](auto go, int i) -> void {
            if (i == 0) {
                ans = min(ans, (int)__builtin_popcount(cur));
                return;
            }
            auto &v1 = below[2 * i];
            auto &v2 = below[2 * i + 1];
            auto &v = below[i];
            v.reserve(v1.size() + v2.size());
            int i1 = 0, i2 = 0;
            bool ok = 1;
            while (i1 < v1.size() && i2 < v2.size()) {
                if (v1[i1] == v2[i2]) {ok = 0; break;}
                if (v1[i1] < v2[i2]) { v.push_back(v1[i1++]); }
                else v.push_back(v2[i2++]);
            }
            if (ok) {
                //debug("ok");
                while (i1 < v1.size()) v.push_back(v1[i1++]);
                while (i2 < v2.size()) v.push_back(v2[i2++]);
                return go(go, i - 1);
            }
            int first = first_unset(__lg(i));
            if (first == n) return;//fail
            cur |= (1 << first);

            below[i] = below[2 * i];
            go(go, i - 1);
            below[i] = below[2 * i + 1];
            go(go, i - 1);

            cur &= ~(1 << first);
        };
        go(go, (1 << n) - 1);
        cout << (ans == n + 1 ? -1 : ans) << '\n';
    }
    return 0;
}