#include<iostream>
#include<string>
#include<queue>
#include<vector>
#include<cassert>
#include<random>
#include<set>
#include<map>
#include<cassert>
#include<unordered_map>
#include<bitset>
#include<numeric>
#include<algorithm>
using namespace std;
typedef long long ll;
const int inf=1<<30;
const ll INF=1LL<<62;
typedef pair<int,ll> P;
typedef pair<int,P> PP; 
const ll MOD=998244353;


ll solve(){
    int N;
    ll X;
    cin>>N>>X;
    vector<int> c(N);
    for(int i=0;i<N;i++) cin>>c[i];
    sort(c.begin(),c.end());
    reverse(c.begin(),c.end());
    //大きい方から見ていく
    int t=-1;
    for(ll v:c){
        if((X>>v)&1) continue;
        else{
            t=v;
            break;
        }
    }
    
    if(t==-1){
        return 0;
    }
    ll ans=INF;
    {
        ll v=(X/(1LL<<t)+1)*(1LL<<t);
        ans=min(ans,abs(v-X));
    }
    {
        ll v=X/(1LL<<t);
        if(v>0){
            v*=(1LL<<t);
            v-=1;
            ans=min(ans,abs(v-X));
        }
    }
    return ans*2;
    
}

int main(){
    int T;
    cin>>T;
    vector<ll> ans(T);
    for(int t=0;t<T;t++){
        ans[t]=solve();
    }

    for(int t=0;t<T;t++){
        cout<<ans[t]<<endl;
    }
}