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

J R Z T F B R
N F J S Q U D
F B H U X L W
Y M K U L H N
C U H I J B Q
I N N N T Z I
A N N N E D H
B N N N X U R
O X O P Q R I

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]>>>.