Tricky bitcount

SQL> -- it's a tricky one... for those who have UTF8
SQL> -- no optimization or whtsoever, just an idea...
SQL> SET VERIFY OFF
SQL> VAR n NUMBER
SQL> VAR i VARCHAR2(30);
SQL> EXEC :i := '0123456789ABCDEF';

PL/SQL procedure successfully completed.

SQL> COLUMN value FORMAT A12
SQL> SELECT value
  2    FROM nls_database_parameters
  3    WHERE parameter = 'NLS_NCHAR_CHARACTERSET'
  4  /

VALUE
------------
UTF8

SQL> SELECT value
  2    FROM nls_database_parameters
  3    WHERE parameter = 'NLS_CHARACTERSET'
  4  /

VALUE
------------
UTF8

SQL> DEFINE b2=C280
SQL> DEFINE b3=E0A080
SQL> DEFINE utf8=&b2&b2&b2&b3&b2&b2&b3&b2&b3&b3
SQL> BEGIN
  2    :n := LENGTHB(
  3            REPLACE(
  4              TRANSLATE(:i
  5                       , '35679ABCDE0'
  6                       , utl_raw.cast_to_nvarchar2('&utf8')
  7                       )
  8            , 'F'
  9            , '1111'
 10            )
 11          );
 12  END;
 13  /

PL/SQL procedure successfully completed.

SQL> PRINT n

         N
----------
        32

SQL> EXEC :i := 'AC001DEADBEEF';

PL/SQL procedure successfully completed.

SQL> /

PL/SQL procedure successfully completed.

SQL> PRINT n

         N
----------
        29