#include <iostream>
#include <vector>
using namespace std;
using ll = long long;

int main() {
    ll T;
    cin >> T;
    while (T--) {
        ll N, X;
        cin >> N >> X;
        vector<ll> c(N);
        for (ll i = 0; i < N; i++) {
            cin >> c[i];
        }
        ll ans = 0;
        for (ll i = N - 1; i >= 0; i--) {
            if (!((X >> c[i]) & 1)) {
                ll bc = (1LL << c[i]);
                ll floor = (X / bc) * bc;     // 切り捨て
                ll ceil = (X / bc + 1) * bc;  // 切り上げ
                if (floor == 0) {
                    ans = (ceil - X) * 2;
                } else {
                    ll min_d = min((ceil - X) * 2, (X - (floor - 1)) * 2);
                    ans = min_d;
                }
                break;
            }
        }
        cout << ans << endl;
    }
}