#include<iostream>
#include<cassert>
using namespace std;
int N,c[60];
long X;
int main()
{
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	int T;cin>>T;
	for(;T--;)
	{
		cin>>N>>X;
		for(int i=0;i<N;i++)cin>>c[i];
		int i=N-1;
		while(i>=0&&(X>>c[i]&1))i--;
		if(i<0)
		{
			cout<<"0\n";
			continue;
		}
		const long t=1L<<c[i];
		long ans=(X/t*t+t-X)*2;
		if(X>>c[i])
		{
			ans=min(ans,(X-(X/t*t-1))*2);
		}
		cout<<ans<<"\n";
	}
}