Largest Uniform Square Subgrid

You are given a grid of characters with r rows and c columns. Your task is to find the area of the largest square subgrid in which all the characters are identical.

Input Format: The first line contains two integers r and c which represent the number of rows and columns respectively. The following r lines each contain a string of length c, representing a row in the grid.

Output Format: Output a single integer representing the area of the largest square subgrid where all cells contain the same character. If no such square exists, output 0.

Note: A square subgrid is defined as a contiguous block of cells forming a square.

Example:

For the grid:

3 4
aaaa
aabb
aabb

The largest uniform square subgrid is of size 2x2 and its area is 4.

The formula for the area of the square is given in LaTeX as: \(Area = side^2\).

inputFormat

The first line contains two space-separated integers, r and c, which represent the number of rows and columns in the grid, respectively.

The next r lines each contain a string of length c consisting of characters.

outputFormat

Output a single integer which is the area of the largest square subgrid that contains the same character.

## sample

3 4
aaaa
aabb
aabb

4

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