package main

import . "fmt"

func main() {
	var t int
	Scan(&t)
	for ; t > 0; t-- {
		var n,k int
		Scan(&n,&k)
		m := 1
		aa := make([]int, n)
		for i := range aa {
			Scan(&aa[i])
			m *= aa[i]
		}
		ans := m
		for _, a := range aa {
			ans = min(ans, m/a*(a-k))
		}
		Println(ans)
	}
}