Rectangle Component Checker

You are given a grid of characters consisting of . and X. The grid represents a pattern where the character X forms a connected component. Your task is to determine whether the connected component of X forms a perfect rectangle.

A connected component forms a rectangle if, when you determine the minimum and maximum row and column indices that contain an X, all cells within that defined sub-grid are filled with an X. If there exists any cell within that rectangle that is not X, the answer is NO; otherwise, it is YES.

Note: A single X is considered as a rectangle of size $1\times1$.

inputFormat

The first line of input contains an integer T (the number of test cases).

Each test case starts with a line containing two integers n and m — the number of rows and columns of the grid, respectively.

This is followed by n lines, each containing a string of length m consisting only of characters . and X, representing the grid.

Input is read from standard input (stdin).

outputFormat

For each test case, output a single line containing either YES if the connected component of X forms a rectangle, or NO otherwise.

Output should be written to standard output (stdout).

## sample

2
4 5
.....
..XX.
..XX.
.....
3 4
..X.
..X.
...X

YES
NO

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