How to Check database size in oracle 8i Version?

break on report on fsmtpt skip 1
compute sum of mtptgb on report
compute sum of nbrfiles on report
compute sum of mtptgb on fsmtpt
col fsmtpt format a6 trunc
col mtptgb format 999.90
col dftype format a6
col nbrfiles format 9999
select 'DF' dftype,count(*) nbrfiles,
substr(f.file_name,8,(instr(f.file_name,'/',9,1) -8)) fsmtpt,
sum(bytes)/1024/1024/1024 mtptgb
from dba_data_files f
group by substr(f.file_name,8,(instr(f.file_name,'/',9,1) -8))
union
select 'TF' dftype,count(*) nbrfiles,
substr(t.file_name,8,(instr(t.file_name,'/',9,1) -8)) fsmtpt,
sum(bytes)/1024/1024/1024 mtptgb
from dba_temp_files t
group by substr(t.file_name,8,(instr(t.file_name,'/',9,1) -8))
union
select 'RL' dftype, count(*) nbrfiles,
substr(lf.member,8,(instr(lf.member,'/',9,1) -8)) fsmtpt,
sum(bytes)/1024/1024/1024 mtptgb
from v$log lg, v$logfile lf
where lf.group# = lg.group#
group by substr(lf.member,8,(instr(lf.member,'/',9,1) -8))
union
select 'CF' dftype, count(*) nbrfiles,
substr(c.name,8,(instr(c.name,'/',9,1) -8)) fsmtpt,
0 mtptgb
from v$controlfile c
group by substr(c.name,8,(instr(c.name,'/',9,1) -8))
order by 3
/