American Express is a good company. I took an online test for this company during a campus placement drive.

The test was pretty simple and comprised of three questions. Two of them were based on 2D matrix problems, and the last question was a medium-level string problem.

Second Question:

Given a 2D matrix of m rows and n columns, a cleaner robot is placed at position (0,0). The robot moves in the forward direction, cleaning tiles ('.') until an obstacle ('#') or the border of the matrix is encountered. It then turns clockwise and moves forward until another obstacle is encountered. Following these rules, the robot forms a cleaning path for itself.

Output the maximum number of tiles the robot can clean for a given matrix.

Constraints:

arr[i][j] is either '#' or '.' 1 <= m <= 20, 1 <= n <= 20 The starting point will always be a tile ('.')