#include <bits/stdc++.h>
#include <atcoder/all>
#include <algorithm>
#include <iostream>
#include <iomanip>
#include <math.h>
#include <random>
#include <chrono>
#include <cstdint>


using namespace std;
using namespace atcoder;
using mint = modint998244353;
// using mint = modint1000000007;
using vi = vector<int>;
using vvi = vector<vector<int>>;
using vvvi = vector<vector<vector<int>>>;
using vl = vector<long long>;
using vvl = vector<vector<long long>>;
using vvvl = vector<vector<vector<long long>>>;
using vm = vector<mint>;
using vvm = vector<vector<mint>>;
using vvvm = vector<vector<vector<mint>>>;
using ll = long long;
template <class T> using max_heap = priority_queue<T>;
template <class T> using min_heap = priority_queue<T, vector<T>, greater<>>;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define rep2(i, f, n) for (int i = (int) f; i < (int)(n); i++)
#define repd(i, n, l) for (int i = (int) n; i >= (int) l; i--)
#define all(p) p.begin(),p.end()
vector<pair<int, int>> dydx{{-1, 0}, {1, 0}, {0, -1 }, {0, 1}};
const ll inf = 1LL << 60;
void print(){ putchar(' '); }
void print(bool a){ printf("%d", a); }
void print(int a){ printf("%d", a); }
void print(unsigned a){ printf("%u", a); }
void print(long a){ printf("%ld", a); }
void print(long long a){ printf("%lld", a); }
void print(unsigned long long a){ printf("%llu", a); }
void print(char a){ printf("%c", a); }
void print(char a[]){ printf("%s", a); }
void print(const char a[]){ printf("%s", a); }
void print(float a){ printf("%.15f", a); }
void print(double a){ printf("%.15f", a); }
void print(long double a){ printf("%.15Lf", a); }
void print(const string& a){ for(auto&& i : a) print(i); }
template<class T> void print(const complex<T>& a){ if(a.real() >= 0) print('+'); print(a.real()); if(a.imag() >= 0) print('+'); print(a.imag()); print('i'); }
template<class T> void print(const vector<T>&);
template<class T, size_t size> void print(const array<T, size>&);
template<class T, class L> void print(const pair<T, L>& p);
template<class T, size_t size> void print(const T (&)[size]);
template<class T> void print(const vector<T>& a){ if(a.empty()) return; print(a[0]); for(auto i = a.begin(); ++i != a.end(); ){ putchar(' '); print(*i); } }
template<class T> void print(const deque<T>& a){ if(a.empty()) return; print(a[0]); for(auto i = a.begin(); ++i != a.end(); ){ putchar(' '); print(*i); } }
template<class T, size_t size> void print(const array<T, size>& a){ print(a[0]); for(auto i = a.begin(); ++i != a.end(); ){ putchar(' '); print(*i); } }
template<class T, class L> void print(const pair<T, L>& p){ print(p.first); putchar(' '); print(p.second); }
template<class T, size_t size> void print(const T (&a)[size]){ print(a[0]); for(auto i = a; ++i != end(a); ){ putchar(' '); print(*i); } }
template<class T> void print(const T& a){ cout << a; }
constexpr ll ten(int n){
	return n==0?1:ten(n-1)*10;
}

vector<vector<int>> unweighted_graph(int n, int m){
    vector<vector<int>> ret(n);
    while (m--){
        int a, b;
        cin >> a >> b;
        a--; b--;
        ret[a].push_back(b);
        ret[b].push_back(a);
    }
    return ret;
}
vector<vector<pair<int, long long>>> weighted_graph(int n, int m){
    vector<vector<pair<int, long long>>> ret(n);
    while (m--){
        int a, b;
        long long c;
        cin >> a >> b >> c;
        a--, b--;
        ret[a].push_back({b, c});
        ret[b].push_back({a, c});
    }
    return ret;
}

template<typename T>
int argmin(vector<T> &a){
    T mi = *min_element(all(a));
    for (int i = 0; i < a.size(); i++){
        if (a[i] == mi) return i;
    }
}

template<typename T>
int argmax(vector<T> &a){
    T ma = *max_element(all(a));
    for (int i = 0; i < a.size(); i++){
        if (a[i] == ma) return i;
    }
}

// void solve(){
//     int n;
//     ll x;
//     cin >> n >> x;
//     vi c(n);rep(i, n) cin >> c[i];

//     for (int i = n-1; i >= 0; i--){
//         if (x & (1LL << c[i])) continue;
//         ll tc = (1LL << c[i]);
//         ll x1 = (x / tc + 1LL) * tc;
//         ll x2 = (x / tc) * tc - 1LL;
//         ll ans = 2 * abs(x1 - x);
//         if (x2 != -1) ans = min(ans, 2 * abs(x - x2));
//         cout << ans << endl;
//         return;
//     }
//     cout << 0 << endl;
//     return;
// }

void solve(){
    int n;
    ll x;
    cin >> n >> x;
    vi c(n);rep(i, n) cin >> c[i];

    for (int i = n-1; i >= 0; i--){
        if (x & (1LL << c[i])) continue;
        // cout << c[i] << endl;
        ll x1 = x;
        rep(j, c[i]){
            if ((x1>>j)&1) {
                x1 ^= (1LL<<j);
                // cout << x1 << endl;
            }
        }
        x1 |= (1LL << c[i]);
        ll x2 = x;
        rep(j, c[i] + 1){
            x2 |= (1LL << j);
        }
        // cout << x1 << ' ' << x2 << endl;
        rep2(j, c[i]+1, 61){
            if (x2 & (1LL << j)){
                x2 ^= (1LL << j);
                rep2(k, c[i]+1, j) x2 |= (1LL << k);
                break;
            }
        }
        
        // cout << x1 << ' ' << x2 << endl;
        cout << min(2 * abs(x - x1), 2 * abs(x - x2)) << endl;
        return;
    }
    cout << 0 << endl;
    return;
}

int main() {
    int t;
    cin >> t;
    while (t--) solve();
    return 0;
}