How to insert record inside the internal table in below code

Question

Hi all,
My requirement is to find the sub-total and need to insert in between the internal table.
You can see the output ....where I want the sub-total F2 when 1 & 2 combindely , 3 , 4& 5 combindely .Please check it and let me know is it possible
when i am using modification  it is not creating extra row inside the table instead it is modifying one row and putting the total there.
For ex: the origianl output is
F1   F2       F3
A      1          1
B      1          1
F      2          1
D      3          1
E      4          1
C      5          1
We want to display all the total of f2 of 1-2 , 3 , 4-5
so expcected output is
F1   F2       F3
A      1          1
B      1          1
F      2          1
     *              3  ->This is the sub-total of 1& 2 of f2
D      3          1
        *           1 ->this is the sub-total of 3
E      4          1
C      5          1
      *             2 -> this is the sub-total of 4 & 5
= space
But coming output is
A 1          1
B 1          1
*             3 -> it is modifying the F row and inserting the total .Total is comong correct but is shoule insert  instead of modifying the record!!
  *           1
E  4          1
*             2
Please help how to insert the row total at the end of the chage of field
Please find the below code ..Due to space problem i am attaching below
Sas

Answer 1

Here is the solution ....i Got the answer Thanks for your helping hands friends
REPORT  YTEST_MODIFY.
DATA: BEGIN OF ITAB OCCURS 1,
TOT TYPE C,
F1 TYPE C,
F2 TYPE C,
F3 TYPE I ,
END OF ITAB.
DATA: BEGIN OF JTAB OCCURS 1,
F1 TYPE C,
F2 TYPE C,
F3 TYPE I ,
END OF JTAB.
START-OF-SELECTION.
  ITAB-F1 = 'A'.
  ITAB-F2 =  1.
  ITAB-F3 =  1.
  APPEND ITAB.
  ITAB-F1 = 'B'.
  ITAB-F2 =  1.
  ITAB-F3 =  1.
  APPEND ITAB.
  ITAB-F1 = 'C'.
  ITAB-F2 =  5.
  ITAB-F3 =  1.
  APPEND ITAB.
  ITAB-F1 = 'D'.
  ITAB-F2 =  3.
  ITAB-F3 =  1.
  APPEND ITAB.
  ITAB-F1 = 'E'.
  ITAB-F2 =  4.
  ITAB-F3 =  1.
  APPEND ITAB.
  ITAB-F1 = 'F'.
  ITAB-F2 =  2.
  ITAB-F3 =  1.
  APPEND ITAB.
  SORT ITAB BY F2.
  LOOP AT ITAB.
    WRITE:/1 ITAB-F1 ,
          8 ITAB-F2 ,
          10 ITAB-F3 .
  ENDLOOP.
  LOOP AT ITAB.
    IF ITAB-F2 = 1 OR ITAB-F2 = 2.
      ITAB-TOT = 1.
      MODIFY ITAB.
    ELSEIF ITAB-F2 = 3.
      ITAB-TOT = 3.
      MODIFY ITAB.
    ELSEIF ITAB-F2 = 4 OR ITAB-F2 = 5.
      ITAB-TOT = 4.
      MODIFY ITAB.
    ENDIF.
  ENDLOOP.
  SKIP 2.
  SORT ITAB BY TOT.
  DATA : L_SUM(2) TYPE C,
         L_ROW(2) TYPE C.
  LOOP AT ITAB.
    MOVE-CORRESPONDING ITAB TO JTAB.
    APPEND JTAB.
    L_SUM = L_SUM + ITAB-F3 .
    AT END OF TOT.
      CLEAR JTAB.
      JTAB-F3 = L_SUM .
      APPEND JTAB.
      CLEAR L_SUM.
    ENDAT.
  ENDLOOP.
  LOOP AT JTAB.
    WRITE:/1 JTAB-F1 ,
          8 JTAB-F2 ,
          10 JTAB-F3 .
  ENDLOOP.
*  DATA: a TYPE i , b .
*  LOOP AT itab.
*    IF b = 0.
*      a = a + itab-f3.
*    ENDIF.
*    AT END OF tot.
*      MOVE space TO itab-f1.
*      MOVE space TO itab-f2.
*      MOVE a TO itab-f3.
*      MODIFY itab .
*      CLEAR a.
*      b = 1.
*    ENDAT.
*    b = 0.
*  ENDLOOP.
*  LOOP AT itab.
*    MOVE-CORRESPONDING itab TO jtab.
*    APPEND jtab.
*  ENDLOOP.
*  ULINE.
*  LOOP AT jtab.
*    WRITE: / jtab-f1 , jtab-f2 , jtab-f3.
*  ENDLOOP.