#!/usr/bin/env ruby

input = (ARGV.first.nil? ? DATA : ARGF)
  .readlines(chomp: true)
  .map { _1.split("-") }

connections = Hash.new { _1[_2] = Set.new }

input.each do |connection|
  a, b = connection.sort

  connections[a] << b
  connections[b] << a
end

parties = Set.new
connections.dup.each do |(node, neighbors)|
  neighbors.each do |neighbor|
    connections[neighbor].each do |neighbors_neighbor|
      if neighbors.include?(neighbors_neighbor)
        parties << [node, neighbor, neighbors_neighbor].sort
      end
    end
  end
end

p parties.select { |party| party.any? { _1.match?(/^t/) } }.size

largest = []
connections.keys.each do |node|
  (connections[node].size + 1).downto(1) do |size|
    (connections[node] + [node]).to_a.combination(size) do |group|
      if group.all? { |a| group.all? { |b| a == b || connections[a].include?(b) } }
        if largest.size < group.size
          largest = group
          break
        end
      end
    end
    break if largest.size == size
  end
end

p largest.sort.join(",")

__END__
kh-tc
qp-kh
de-cg
ka-co
yn-aq
qp-ub
cg-tb
vc-aq
tb-ka
wh-tc
yn-cg
kh-ub
ta-co
de-co
tc-td
tb-wq
wh-td
ta-ka
td-qp
aq-cg
wq-ub
ub-vc
de-ta
wq-aq
wq-vc
wh-yn
ka-de
kh-ta
co-tc
wh-qp
tb-vc
td-yn