#!/usr/bin/ruby

#
# See https://theweeklychallenge.org/blog/perl-weekly-challenge-154
#
 
#
# Run as: ruby ch-1.rb < input-file
#

p = {
  "PERL" => 1, "PELR" => 1, "PREL" => 1, "PRLE" => 1, "PLER" => 1, "PLRE" => 1,
  "EPRL" => 1, "EPLR" => 1, "ERPL" => 1, "ERLP" => 1, "ELPR" => 1, "ELRP" => 1,
  "REPL" => 1, "RELP" => 1, "RPEL" => 1, "RPLE" => 1, "RLEP" => 1, "RLPE" => 1,
  "LERP" => 1, "LEPR" => 1, "LREP" => 1, "LRPE" => 1, "LPER" => 1, "LPRE" => 1,}

ARGF . each_line do |word|
    p . delete(word . strip())
end

p . keys . map do |x|
    puts (x)
end