Table in GUI - limit the user to enter only one value (+other special cases)

Hello!

I am using on my interface a table (30x30 cell array). Now I have tree cases: 1) limit the user to introduce one single value (1x1 cell array). Otherwise a message error will appear. 2) limit the user to enter a line vector (1xa cell array - where a>1 and a<=30) or a column vector(bx1 - where b>1 and b<=30). Otherwise a message error will appear. 3) limit the user to enter a vector of size aXa - where a>=2 and a<=30. Otherwise a message error will appear.

I am blocked here.. Thanks in advance!