t = int(input())
for tt in range(0,t):
    n,m = map(int,input().split())
    arr = list(map(int,input().split()))
    a = 1
    for i in range (0,n):
        a *= arr[i]
    mini = a 
    for i in range(0,n):
        k = a 
        a//=arr[i]
        arr[i]-=m
        a*=arr[i]
        mini = min(a,mini)
        a = k 
    print(mini)