Alter User not working in oracle -

i'm doing follwing question

managing locked accounts – utility should able identify each locked  account locked because of invalid login attempts. utility should further  unlock accounts have been locked more week. 

----------------------------------------my code------------------------------------------

procedure managing_locked num int; v_sql varchar(50); begin  x in (select username,lock_date,account_status,profile  dba_users account_status ='locked(timed)') loop     dbms_output.put_line('username: '|| x.username);     dbms_output.put_line('lock_date:  '|| x.lock_date );     dbms_output.put_line('account_status: '||x.account_status);     dbms_output.put_line('profile: ' ||x.profile);     dbms_output.put_line('*********************');      select ((sysdate - x.lock_date))  num dual;      if(num>7)                 v_sql := 'alter user'|| x.username ||'account unlock';          dbms_output.put_line(x.username||' unlock');       execute immediate(v_sql);       end if;     end loop; end; 

error 00940. 00000 - "invalid alter command"

i getting error , don't see wrong alter command

just in order catch each possible status clause should one:

where account_status in (    'locked(timed)',     'expired & locked(timed)',    'expired(grace) & locked(timed)') 

or

where account_status '%locked(timed)'