T = int(input())

INF = 10**18
for _ in range(T):
    N, X = map(int, input().split())
    C = list(map(int, input().split()))
    L = []
    for i in range(N):
        if not 1<<C[i] & X:
            if X>>C[i] == 0:
                L.append((INF, i))
            else:
                L.append((X%(1<<C[i])+1, i))
    if len(L) == 0:
        print(0)
        continue
    R = []
    for i in range(N):
        if not 1<<C[i] & X:
            R.append(((1<<C[i])-X%(1<<C[i]), i))
    L.sort(key=lambda x:x[0])
    ans = max(r[0] for r in R)*2
    S = set()
    for i in range(len(L)):
        left, idx = L[i]
        S.add(idx)
        right = 0
        for j in range(len(R)):
            r, idxR = R[j]
            if idxR not in S:
                right = max(right, r)
        ans = min(ans, left*2+right*2)
    print(ans)