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

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

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]>>>.