G
:
s/\n/&X/
/b/s/\(x\)\(x*\)/\2\1/i
/d/s/\(x\{21\}\)\(x*\)/\2\1/i
/f/s/\(x*\)\(x\{22\}\)/\2\1/i
s/X/xabc@/463
/@/{y/\n@abcdef/--bcdefa/
/1-/y/abcdef/efabcd/
b}
s/-x/1@X/
s/-X/0@x/
s/1\|@.*//447
t
Note that non-ascii characters in the above source code will be escaped (such as \x9f).