Using where clause for long column

We have a 10204 database and I'm running this query but it error out. I want to get the last partition_name but unable to get it. Is there a way to get it in varchar2 format?

SQL> l
  1  select max(partition_position)  from dba_tab_partitions
  2  where table_owner='CARSDM'
  3  and table_name='CARS_ON_SERVPHONE_MSS'
  4* and high_value !='MAXVALUE'
SQL> /
and high_value !='MAXVALUE'
    *
ERROR at line 4:
ORA-00997: illegal use of LONG datatype

SQL> set long 99999
SQL> /
and high_value !='MAXVALUE'
    *
ERROR at line 4:
ORA-00997: illegal use of LONG datatype

SQL> l
  1  select max(partition_position)  from dba_tab_partitions