mg5c

m=size(a,1);
n=size(a,2);
b=0;
for i=1:m
for j=1:n
for k=1:m-i+1
for l=1:n-j+1
c=a(k:k+i-1,l:l+j-1);
if all(c==c(1))
s=sum(sum(c));
b=max(s,b);
end
end
end
end
end