How can i have a matrix A, that depends of the result of other matrix B, that when there's a x number in B, matrix A changes to 1

So, i have a matrix B(51,10,1000), that have somewhere negative numbers.

And i want a matrix A(51,1000) that when running the matrix B, it gives me a value "1" if it's negative in B. And after there's one "1", all the other lines of A become "2". And if there's is not a negative value the libe of A is "0".

I don't know how to put the part when if there's one 1, all the lines are equal to 2.

something like:

A =[ 0 0 0 0 1 2 2 2 2 ] (this would be a column)

for k= 1:1000

      for i = 1:51

          for j = 1:10

              if B(i,j,k)<=0
                  A(i,k) =1;
                break
              else 
                  A=(i,k) = 0;
              end

          end
      end
  end

Answer 1

[Matt J]

A=cumsum(cumsum(B<0,1),1);

A(A>=2)=2;