I have been trying to run postgresql server on the first time on my PC. It actually had a prior installation but I removed it and reinstalled it.

Now my pg_hba and postgresql.conf files can be found here..

Whenever, I run su postgres -c psql postgres, it asks for a password, I am not sure what should I enter over here.
Is there a default password or is there a way to reset the password again.

HTML Code:
_______@linux-x4vi:~/Downloads> su postgres -c psql postgres
su: Authentication failure
I also do not remember creating a user named postgres as can be seen here.

drwxr-x--- 4 postgres postgres 4096 Sep 22 12:36 .
drwxr-xr-x 49 root root 4096 Sep 22 12:30 ..
-rw------- 1 postgres postgres 332 Aug 22 14:59 .bash_history
-rw-r----- 1 postgres postgres 192 Feb 28 2014 .bash_profile
drwxr-xr-x 3 postgres postgres 4096 Aug 12 15:14 .local
-rw------- 1 postgres postgres 109 Aug 13 11:08 .psql_history
drwx------ 15 postgres postgres 4096 Sep 22 15:10 data
-rw-r--r-- 1 postgres postgres 1228 Aug 12 15:14 initlog