#23456789_123456789_123456789_123456789_1234
perl -nlE'unpack("%c*",$_&"\c_"x30)-65||say' words.txt

##</code><code>##

#23456789_123456789_123456789_123456789_12
perl -nlE'65^unpack"%c*",$_&~"`"x30or say' words.txt

##</code><code>##

#23456789_123456789_123456789_123456789_12
perl -nlE'65^unpack"%c*",$_&v31 x30or say' words.txt