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

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

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]>>>.