#!/usr/bin/env ruby

problem = 5
input = File.readlines("#{problem}.input").map(&:strip)
#input = DATA.read.split("\n")
split = input.index("")

rules = input[0...split].map { _1.split("|").map(&:to_i) }
page_sets = input[split+1..].map { _1.split(",").map(&:to_i) }

result = page_sets.select do |page_set|
  rules
    .select { |a| (page_set & a).sort == a.sort }
    .all? { |(a, b)| page_set.index(a) < page_set.index(b) }
end.map { _1[_1.size / 2] }.sum

p result

__END__
47|53
97|13
97|61
97|47
75|29
61|13
75|53
29|13
97|29
53|29
61|53
97|53
61|29
47|13
75|47
97|75
47|61
75|61
47|29
75|13
53|13

75,47,61,53,29
97,61,53,29,13
75,29,13
75,97,47,61,53
61,13,29
97,13,75,29,47