s/$/<1>abc/
:
/.\{468\}/!s/1/10/
t
/b/s/<\(.\)\(\w*\)/<\2\1/
/d/s/<\(.\{21\}\)\(\w*\)/<\2\1/
/f/s/<\(.\{441\}\)\(\w*\)/<\2\1/
/>/{y/>abcdef/=bcdefa/
/1</y/abcdef/efabcd/
b}
s/<0/0-1/
s/<1/1-0/
y/-=/<>/
/^.\{1468\}/!b
s/<.*//
Note that non-ascii characters in the above source code will be escaped (such as \x9f).