#include<bits/stdc++.h>
#define ll long long
#define inf 0x3f3f3f3f
#define rep(i,a,b) for(int i=(a),i##_end=(b);i<=i##_end;++i)
#define dep(i,a,b) for(int i=(a),i##_end=(b);i>=i##_end;--i)
using namespace std;
template<class T>inline T mymin(T x,T y){return x<y?x:y;}
template<class T>inline T mymax(T x,T y){return x>y?x:y;}
template <typename T>
inline void read(T &X){
    X=0;int w=0; char ch=0;
    while(!isdigit(ch)) {w|=ch=='-';ch=getchar();}
    while(isdigit(ch)) X=X*10+(ch^48),ch=getchar();
    if(w) X=-X;
}
const int maxn = 4e5 + 5;
//const double pi = acos(-1.0);
//const double eps = 1e-9;
//const int mo = 1e9 + 7;
int n,m,k,q;
int a[maxn],c[maxn],d[maxn];
int ans,tmp,cnt,num;
int flag;
vector<int>vc[maxn];
void dfs(int pos,int cnt,int ans,int upd){
    if(ans >= tmp) return;
    if(pos == 1){
        tmp = ans;
        return;
    }
    if(pos == k - cnt){
        upd++;
        k -= cnt;
        cnt >>= 1;
    }
    // cout<<"???: "<<pos<<" "<<cnt<<" "<<ans<<endl;
    int r = -1;
    unordered_map<int,int>mp;
    int i = pos;
    for(int v:vc[i]) mp[v] = 1;
    for(int v:vc[i - 1]) if(mp[v]) {
        r = i;
        break;
    }
    int sz = vc[i / 2].size();
    if(r < 0){
        for(int v:vc[i]) vc[i / 2].emplace_back(v + a[i / 2]);
        for(int v:vc[i - 1]) vc[i / 2].emplace_back(v + a[i / 2]);
        dfs(pos - 2,cnt,ans,upd);
        while(vc[i/2].size() > sz) vc[i/2].pop_back();

        if(upd > 0){
            int sz = vc[i/2].size();
            for(int v:vc[i]) vc[i / 2].emplace_back(v + a[i / 2]);
            dfs(pos - 2,cnt,ans + 1,upd - 1);
            while(vc[i/2].size() > sz) vc[i/2].pop_back();
            
            sz = vc[i/2].size();
            vc[i / 2].clear();
            for(int v:vc[i - 1]) vc[i / 2].emplace_back(v + a[i / 2]);
            dfs(pos - 2,cnt,ans + 1,upd - 1);
            while(vc[i/2].size() > sz) vc[i/2].pop_back();
        }
    }else{
        if(!upd) return;
        int sz = vc[i/2].size();
        for(int v:vc[i]) vc[i / 2].emplace_back(v + a[i / 2]);
        dfs(pos - 2,cnt,ans + 1,upd - 1);
        while(vc[i/2].size() > sz) vc[i/2].pop_back();
            
        sz = vc[i/2].size();
        vc[i / 2].clear();
        for(int v:vc[i - 1]) vc[i / 2].emplace_back(v + a[i / 2]);
        dfs(pos - 2,cnt,ans + 1,upd - 1);
        while(vc[i/2].size() > sz) vc[i/2].pop_back();
    }
}
void solve(){
    read(n);
    n++;
    m = (1 << n) - 1;
    k = m;
    rep(i,2,m){
        read(a[i]);
    }
    rep(i,0,m + 1){
        vc[i].clear();
    }
    rep(i,0,n) c[i] = 0;
    num = (1 << (n - 1));
    
    for(int i = m; i > m - num; i --){
        vc[i].emplace_back(a[i]);
    }
    tmp = n + 1;
    dfs(m,num,0,1);
    if(tmp > n) tmp = -1;
    printf("%d\n",tmp);
}
int main(){
    //cin.tie(0)->sync_with_stdio(false);
    int T=1,cas=1;
    read(T);
    while(T--) solve();
    return 0;
}