別解 [Ruby]

require 'net/http'

Net::HTTP.version_1_2   
text = Net::HTTP.start('www.pythonchallenge.com', 80) {|http|
  response = http.get('/pc/def/equality.html')
  response.body
}

p text.split("\n").collect { |node|
  next unless (node =~ /[^A-Z][A-Z]{3}([a-z])[A-Z]{3}[^A-Z]/)
  "#{$1}"
}.join

require 'net/http'

Net::HTTP.version_1_2   
text = Net::HTTP.start('www.pythonchallenge.com', 80) {|http|
  response = http.get('/pc/def/equality.html')
  response.body
}

text.each_line("\n") { |line|
  next unless (line =~ /[^A-Z][A-Z]{3}([a-z])[A-Z]{3}[^A-Z]/)
  print "#{$1}"
}