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

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]>>>.