def solve():
    n,x=map(int,input().split())
    c=list(map(int,input().split()))
    for I in range(n):
        i=n-I-1
        if (x>>c[i]&1)==False:
            bc=1<<c[i]
            floor=(x//bc)*bc
            ceil=(x//bc+1)*bc
            if(floor==0):
                return (ceil-x)*2
            else:
                return min((ceil-x)*2,(x-(floor-1))*2)
    return 0

t=int(input())
for _ in range(t):
    print(solve())