how to put serial numbers to data rows

suppose i have a worksheet in which i have some data in col B with a header on B1.
there are blank rows in between data.i want to give serial numbers to col A irespective of the fact that whether it has data on its right side or it is a blank one.

i put 1 in col A2. i put =then i click on A2 and then input +1.
then i press f5 and put A24 pressed the shift key and pressed enter. then i pressed control D.as a result , i get serial numbers from 1 to 24 in col A.

(suppose there are only 10 data rows and others are blanks.)
now i want to eliminate the blank rows keeping the serial numbers(in col A) of the data rows in place.

now i enter =COUNTA(B2) in col C.i copy the formula to the last row of data.
i get 1 against data rows and zero against blank rows.

now i apply autofilter to col A1 select zero in col C. i get all blank rows together. i delete them.
now i get the data without the blank rows. the problem i face is that
the serial number in col A has disappeared. it says problem with the cell reference. now let me ask whether it is possible to do this task with the serial numbers in place( of course the numbers will be minus the blank rows,like 1,2,4,7,12..... i don't mind)

-----------------------------
A B C
-----------------------------
SL.NO TITLE
-----------------------------
1 abc 1
2 wett 1
3 0
4 jkhghj 1
5 0
6 0
7 rloljo 1
8 0
9 0
10 fddde 1
11 0
12 rderu 1
-------------------------------

Put this in A2 and copy down:

=MAX(A$1:A1)+1