A path in a grid is called greedy if it starts at the top-left cell and moves only to the right or downward, always moving to its neighbor with the greater value (or either if the values are equal). The value of a path is the sum of the values of the cells it visits, including the start and end. Given a partially filled (2 \times n) grid of integers between (1) and (k), count the number of ways to fill the empty cells such that in every subgrid (^{\text{∗}}), there exists a greedy path that achieves the maximum value out of all down/right paths. Since the answer may be large, calculate it modulo (998\,244\,353). (^{\text{∗}}) A subgrid of a (2 \times n) grid (a_{i,j}) is a grid formed from all cells (a_{x,y}) such that (l_x \leq x \leq r_x), (l_y \leq y \leq r_y) for some (1 \leq l_x \leq r_x \leq 2), (1 \leq l_y \leq r_y \leq n). Each test contains multiple test cases. The first line contains the number of test cases (t) ((1 \le t \le 500)). The description of the test cases follows. The first line of each test case contains two integers (n) and (k) ((1 \leq n, k \leq 500)) — the number of columns and the range of integers in the grid, respectively. Then two lines follow, the (i)-th line containing (n) integers (a_{i,1}, a_{i,2}, \ldots, a_{i,n}) ((-1 \leq a_{i,j} \leq k), (a_{i,j} \neq 0)) — the values of cells in the (i)-th row of the grid, where (-1) represents an empty cell. It is guaranteed that the sum of (n) over all test cases does not exceed (500). For each test case, output a single integer — the number of ways to fill the grid that satisfy the above conditions, modulo (998\,244\,353). In the first test case, the grids that satisfy the conditions are: () \begin{bmatrix} 2 & 1 & 1 & 2 \\ 2 & 1 & 1 & 3 \end{bmatrix},\: \begin{bmatrix} 2 & 1 & 1 & 2 \\ 2 & 2 & 1 & 3 \end{bmatrix},\: \begin{bmatrix} 2 & 1 & 1 & 2 \\ 2 & 3 & 1 & 3 \end{