E. Binary String Wowee
time limit per test
2 seconds
memory limit per test
256 megabytes
input
standard input
output
standard output

Mouf is bored with themes, so he decided not to use any themes for this problem.

You are given a binary$$$^{\text{∗}}$$$ string $$$s$$$ of length $$$n$$$. You are to perform the following operation exactly $$$k$$$ times:

  • select an index $$$i$$$ ($$$1 \le i \le n$$$) such that $$$s_i = \mathtt{0}$$$;
  • then flip$$$^{\text{†}}$$$ each $$$s_j$$$ for all indices $$$j$$$ ($$$1 \le j \le i$$$).

You need to count the number of possible ways to perform all $$$k$$$ operations.

Since the answer could be ginormous, print it modulo $$$998\,244\,353$$$.

Two sequences of operations are considered different if they differ in the index selected at any step.

$$$^{\text{∗}}$$$A binary string is a string that consists only of the characters $$$\mathtt{0}$$$ and $$$\mathtt{1}$$$.

$$$^{\text{†}}$$$Flipping a binary character is changing it from $$$\mathtt{0}$$$ to $$$\mathtt{1}$$$ or vice versa.

Input

Each test contains multiple test cases. The first line contains the number of test cases $$$t$$$ ($$$1 \le t \le 100$$$). The description of the test cases follows.

The first line of each test case contains two integers $$$n$$$ and $$$k$$$ ($$$1 \le k \le n \le 500$$$) — the length of the binary string $$$s$$$ and the number of times the operation must be performed, respectively.

The second line of each test case contains a binary string $$$s$$$ of length $$$n$$$ consisting of only characters $$$\mathtt{0}$$$ and $$$\mathtt{1}$$$.

It is guaranteed that the sum of $$$n$$$ does not exceed $$$500$$$ over all test cases.

Output

For each test case, output a single integer — the number of ways you can perform exactly $$$k$$$ operations, modulo $$$998\,244\,353$$$.

Example
Input
5
3 1
010
3 2
000
5 4
01001
8 8
11001100
20 20
10010110101101010110
Output
2
3
10
27286
915530405
Note

In the first test case, here are all the possible sequences of operations:

  • $$$\mathtt{\color{red}{0}10} \xrightarrow{i = 1} \mathtt{110}$$$
  • $$$\mathtt{\color{red}{010}} \xrightarrow{i = 3} \mathtt{101}$$$

In the second test case, here are all the possible sequences of operations:

  • $$$\mathtt{\color{red}{0}00} \xrightarrow{i = 1} \mathtt{\color{red}{1}00} \xrightarrow{i = 2} \mathtt{010}$$$
  • $$$\mathtt{\color{red}{0}00} \xrightarrow{i = 1} \mathtt{\color{red}{1}00} \xrightarrow{i = 3} \mathtt{011}$$$
  • $$$\mathtt{\color{red}{00}0} \xrightarrow{i = 2} \mathtt{\color{red}{11}0} \xrightarrow{i = 3} \mathtt{001}$$$