import sys
input = sys.stdin.readline

T=int(input())

for tests in range(T):
    N,X=map(int,input().split())
    C=list(map(int,input().split()))

    MAX=X

    for c in C:
        if (1<<c) & X !=0:
            continue
        k=2**c

        a=(X+k-1)//k
        if a%2==0:
            a+=1
        MAX=max(MAX,a*k)

    MIN=1<<60

    for c in C:
        if (1<<c) & X !=0:
            continue
        k=2**c

        a=X//k
        if a%2==0:
            a-=1

        if a<0:
            MIN=-1<<60
        else:
            MIN=min(MIN,a*k)

    ANS=min(MAX-X,abs(X-MIN))

    print(ANS*2)