Add value in a matrix

Hi, I need to add a row of values to an array, taking into account the last row of my array (once sorted) I want the next row to show a number starting at 1 that is related to the previous row. Here is an example to try to explain it better

% First matrix
Z = [255 1 0 255 255 255 1
    30 51 51 30 29 29 21
    49 51 52 48 51 52 48
    -5 4 4 -5 -4 -4 4];

% Orderly matrix in the 4th row
ZORD = [255 255 255 255 1 0 1
    30 30 29 29 21 21 21
    49 48 51 52 51 52 48
    -5 -5 -4 -4 4 4 4];

% So far I know how to do it, but this is what I put in now is what
% I only know how to do with a for-loop but for my data size it is not very operational. 
ZFIN = [255,255,255,255,1,0,1;
    30,30,29,29,21,21,21;
    49,48,51,52,51,52,48;
    -5,-5,-4,-4,4,4,4;
    1 1 2 2 3 3 3]

If someone knows how to do the last step I would be very grateful, thank you very much

Answer 1

[JESUS DAVID ARIZA ROYETH]

ZORD=sortrows(Z',4)';
[~,~,C]=unique(ZORD(end,:));
ZFIN=[ZORD; C']

[Alejandro Fernández]

Thank you so much!