#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
using ll=long long;

int main()
{
    int t;
    cin>>t;
    while(t--){
        int n;
        ll x;
        cin>>n>>x;
        vector<int> c(n);
        for(int i=0;i<n;i++)cin>>c[i];
        sort(c.rbegin(),c.rend());
        ll ans=0;
        for(int i=0;i<n;i++){
            if(x>>c[i]&1)continue;
            else{
                ll t=1LL<<62;
                t=min(t,((x>>(c[i]+1))<<(c[i]+1))+(1<<c[i])-x);
                if(x>=(1LL<<c[i])) t=min(t,x-((x>>(c[i]+1))<<(c[i]+1))+1);
                ans=t*2;
                break;
            }
        }
        cout<<ans<<endl;
    }
}