:1
y/0123456789/!012345678/
s/\w/&-/g
t1
:
s/-\{37\}/=/
s/-\(!=*\)/\1----------/
t
s/\W*/&Azyxwvutsrqponmlkjihgfedcba9876543210 /
s/[^!=]\{36\}\(.\).* /\1/
y/=/-/
/-/b
s/!*//
Note that non-ascii characters in the above source code will be escaped (such as \x9f).