You are given an $m \times n$ integer matrix grid, along with three integers x, y, and k.

There is a $k \times k$ square submatrix with its top left corner located at row x and column y.

Flip this square submatrix vertically by reversing the order of its rows while keeping the columns unchanged.

Return the modified grid.

Constraints:

• m $==$ grid.length

• n $==$ grid[i].length

• $1 \le$ m, n $\le 50$

• $1 \le$ grid[i][j] $\le 100$

• $0 \le$ x $<$ m

• $0 \le$ y $<$ n

• $1 \le$ k $\le \min($m $-$ x, n $-$ y$)$

Now, let’s take a moment to make sure you’ve correctly understood the problem. The quiz below helps you check if you’re solving the correct problem:

We have a game for you to play. Rearrange the logical building blocks to develop a clearer understanding of how to solve this problem.

Implement your solution in the following coding playground.