t = int(input())
for _ in range(t):
    n, k = map(int, input().split())
    a = list(map(int, input().split()))
    ans = float('inf')
    for i in range(n):
        a[i] -= k
        costs = 1
        for x in a:
            costs *= x
        ans = min(ans, costs)
        a[i] += k
    print(ans)