s/^10/8/
:
s/[1-9]/&-/g
y/123456789/012345678/
s/-0/9-/
t
s/0//
s/-,-/,/
t
/^,-/c0
:3
s/\W/<<123456789-01>/
s/\(.\)<.*\1\(-*.\).*>/\2/
t3