I hope this is what you want..
I assume k=4 and made A{4} with 14 numbers and expected so expected solution is 14.
k=4;
A=[];
A{1}=[2;8;1;1] ;
A{2}=[1;3;5;4;5;2];
A{3} = [4,5,3,2,5,3,1];
A{4}=[4,5,3,2,5,3,1,4,5,3,2,5,3,1];
S=zeros(1,k);
for i=1:k
s=(size(A{i}));
S(1,i)=max(s);
end
S
