In the mid of main adpatch you got error for applying pre patch,So How to apply the pre_patch

We apply the adpatch and in the mid we get error for applying pre patch,Then how to apply prepatch.
 
Solution:
1.take Backup of fnd_install_process,ad_deffered_jobs table and .rf9 files..
2.after taking backup drop those tables and .rf9 files
3.apply the prerequisite patch through adpatch only
4.after completion of prerequisite patch..restore those two tables and .rf9 files.
5.after restoring run the command adpatch
in this case it will ask for the previous session was not copleted..do u wish to continue ..like that..there u enter yes.than it will automatically start the main patch from where u stoped..