Lost Oracle10g SYS and SYSTEM password?

$ sqlplus "/ as sysdba"

SQL*Plus: Release 10.1.0.2.0 - Production on Tue July 22 14:53:27 2008

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Connected to:
Oracle Database 10g Enterprise Edition Release 10.1.0.2.0 - Production
With the Partitioning, OLAP and Data Mining options

SQL> show user
USER is "SYS"

SQL> passw system
Changing password for system
New password:
Retype new password:
Password changed
SQL> quit