#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;
int flag;
char s[maxn];
bool ok[maxn];
vector<int>vc[maxn];
void dfs(int i,int dep){
    if(dep == n) {
        vc[i/2].emplace_back(a[i]);
        return;
    }
    dfs(i * 2,dep + 1);
    dfs(i * 2 + 1,dep + 1);
    sort(vc[i].begin(),vc[i].end());
    int sz = vc[i].size();
    rep(j,0,sz - 1){
        if(j == 0 || vc[i][j] != vc[i][j - 1]){
            vc[i/2].emplace_back(vc[i][j]+a[i]);
        }else{
            c[dep]++;
        }
    }
}
void solve(){
    read(n);
    n++;
    m = (1 << n) - 1;
    rep(i,2,m){
        read(a[i]);
    }
    rep(i,0,m + 1){
        vc[i].clear();
    }
    rep(i,0,n) c[i] = 0;
    dfs(1,1);
    int ans = 0;
    rep(i,1,n - 1){
        if(c[i]) {c[i]--;ans++;}
        c[i + 1] += c[i];
    }
    if(c[n]){
        puts("-1");
        return;
    }
    printf("%d\n",ans);
}
int main(){
    //cin.tie(0)->sync_with_stdio(false);
    int T=1,cas=1;
    read(T);
    while(T--) solve();
    return 0;
}