T = int(input())
for i in range(T):
    n, k = map(int, input().split())
    a = list(map(int, input().split()))
    ans = float("inf")
    for j in range(n):
        a[i] -= k
        cost = 1
        for x in a:
            cost *= x
        ans = min(ans, cost)
        a[i] += k
    print(ans)