1693  CHOOSE NUMBER
Time Limit : 1 Second
Memory Limit : 128 MB
Submission: 98
Solved: 21
 Description
lxk has n cards and there is a integer number x_{i }on each card. Now his girl lover gives him a card with a number k. She tells lxk to choose k numbers from his cards and the sum of the numbers is a prime number. For example, when n = 4,k = 3, and the set of x_{i }is 3,7,12,19, the only feasible solution is 3 + 7 + 19 = 29. Now you need to calculate how many feasible solutions are there.
 Input
First, you will got an integer T, which means the number of tests. There are multiple sets of tests. In each tests, the first line contains two numbers, n and k, and the next line are n numbers x_{i}.
1 ≤ n ≤ 18, 1 ≤ k ≤ n, 1 ≤ x_{i }≤ 10000
 Output
For each tests, you should first output ”Case #x: ” and then output a number s, which means the number of feasible solution.
 sample input

1 4 3 3 7 12 19
 sample output

Case #1: 1
 hint
 source
 hexing