sed ':0
s/[1-9]/&=/g
y/123456789/012345678/
s/=0/9=/
t0
s/0//2g
:
s/= =/ /
t
s/0 =/+=/
/= /s/^/-/
s/\(.\)<.*\1\(=*.\).*>\| /\2/
s/=/<<123456789=01>/
t'