Converting to columnar output

Hi All,

I need some help in script or awk to create a textfile.

I have a directory where two subdirectories exists say A and B.
Now I need to write a ".txt" file with well arranged(space wraped) three columns in it with the data as follows:

1st column:Serial number(which will increment with the row number)
2nd column:With the filenames of those files existing inside directory A (I do have subfolders inside A)
3rd column:With the filenames of those files existing inside directory B (here also same problem, I have subfolders inside B).

I tried outputing ls * and manipulating .. but was stuck in subfolders..

If this is the input...
(think of nesting as in the directory structure)

animals
  humans
    Joe
    John
    Mary
  dogs
  cats
fruits
  apples
    red
    granny
  banana

then output =
????

INPUT:

Now the output is I require:-

Now I am able to get all the output.
Only thing remaning is arranging them into three columns.

What I have done is something like this:

find /animals/humans -type f|awk -F/ '{print $NF}'>animals.lst

find /animals/fruits -type f|awk -F/ '{print $NF}'>fruits.lst

Thanks in anticipation.

if u have a data:

then result shud be like:
Column1 Column2 Column3
--------- -------- ----------

That is using the three blank lines I want to separate the column to three.