: a
s/^0*/d/
/^d[1-9]/t b
b e
: b
s/d[01]/0&/
s/d[23]/1&/
s/d[45]/2&/
s/d[67]/3&/
s/d[89]/4&/
t d
b a
: c
s/D[01]/5&/
s/D[23]/6&/
s/D[45]/7&/
s/D[67]/8&/
s/D[89]/9&/
t d
b a
: d
s/[dD][02468]/d/
t b
s/[dD][13579]/D/
t c
: e
s/^dD/D/
y/dD/01/