#include<bits/stdc++.h>

#define ll long long
#define pi pair<int,int>
#define vi vector<int>
#define cpy(x,y,s) memcpy(x,y,sizeof(x[0])*(s))
#define mset(x,v,s) memset(x,v,sizeof(x[0])*(s))
#define all(x) begin(x),end(x)
#define fi first
#define se second
#define mp make_pair
#define pb push_back
#define ary array
#define eb emplace_back
#define IL inline
#define For(i,j,k) for(int i=(j);i<=(k);i++)
#define Fol(i,k,j) for(int i=(k);i>=(j);i--)

using namespace std;

#define N 500005

int read(){
    int x=0,f=1;char ch=getchar();
    while(ch<'0' || ch>'9')f=(ch=='-'?-1:f),ch=getchar();
    while(ch>='0' && ch<='9')x=(x<<1)+(x<<3)+(ch^48),ch=getchar();
    return x*f;
}
void write(int x){
    if(x<0)x=-x,putchar('-');
    if(x/10)write(x/10);
    putchar(x%10+'0');
}

void debug(auto &&...x){
    ((cerr<<x<<' '),...);
    cerr<<'\n';
}


int a[N],buc[N];

void solve(){
    int n=read();n++;
    For(i,2,(1<<n)-1)a[i]=read(),a[i]+=a[i/2];
    int res=n-1;
    for(int len=2;len<=(1<<(n-1));len<<=1){
        for(int j=(1<<(n-1));j<(1<<n);j+=len){
            For(k,j,j+len/2-1)buc[a[k]]++;
            For(k,j+len/2,j+len-1)if(buc[a[k]])res--;
            For(k,j,j+len/2-1)buc[a[k]]=0;
        }
        if(n-1-res>len-1){res=-1;break;}
    }
    if(res<0)write(-1);
    else write(n-1-res);putchar('\n');
    For(i,2,(1<<n)-1)a[i]=0;
}

int main(){
    #ifdef EAST_CLOUD
    freopen("a.in","r",stdin);
    //freopen("a.out","w",stdout);
    #endif
 
    int T=read();while(T--)solve();

}