Given a character matrix, your task is to identify the positions of all squares with a length of at least 3 and output the row and column numbers of the bottom-right corner of these squares. The squares are composed of the same character, and each side has a length of at least 3.

If the matrix is

U O W N E P V H
T T T T T N N C
T T T B K P I Q
T T T Y T K H C
O U Y X E K G E
E K O E X F B X
P X T K L W H U

Please provide the row and column of the bottom-right vertex of the square in the character matrix with a side length of at least 3 (the answer is unique). Notice: All coordinates start from 0.  

Your answer should be in the format <<<[row, column]>>>.