perl -lnE'unpack("%a*")-65-96*length||say'

##</code><code>##

perl -lne'65+length()*96-unpack"%a*"or print'

##</code><code>##

perl -lne'65+length()*96-unpack"%a*",lc or print'

##</code><code>##

#23456789_123456789_123456789_123456789_
perl -lnE'65+96*y///c-unpack"%a*"or say'