#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const int INF = 1e9 + 10;
const ll INFL = 4e18;

ll solve() {
    int N;
    ll X;
    cin >> N >> X;
    vector<int> C;
    for (int i = 0, x; i < N; i++) {
        int c;
        cin >> c;
        if (int x = X >> c & 1; !x) {
            C.push_back(c);
        }
    }
    N = C.size();

    if (N == 0) {
        return 0;
    }

    int tgt = C.back();
    ll ans = INFL;

    // 大きい方向に買いに行く Xより大きい、最小の2^tgtの倍数
    {
        ll goal = ((X + (1ll << tgt) - 1) / (1ll << tgt)) * (1ll << tgt);
        ans = min(ans, (goal - X) * 2);
    }
    // 小さい方向
    {
        ll goal = (X / (1ll << tgt)) * (1ll << tgt);
        ans = min(ans, (X - goal) * 2);
    }

    return ans;
}

int main() {
    int T;
    cin >> T;

    while (T--) {
        cout << solve() << endl;
    }
}