;; Santa's reindeer typically eat regular reindeer food, but
;; they need a lot of magical energy to deliver presents on
;; Christmas. For that, their favorite snack is a special
;; type of star fruit that only grows deep in the jungle.
;; The Elves have brought you on their annual expedition to
;; the grove where the fruit grows.
;; To supply enough magical energy, the expedition needs to
;; retrieve a minimum of fifty stars by December 25th.
;; Although the Elves assure you that the grove has plenty
;; of fruit, you decide to grab any fruit you see along the
;; way, just in case.
;; Collect stars by solving puzzles. Two puzzles will be
;; made available on each day in the Advent calendar; the
;; second puzzle is unlocked when you complete the first.
;; Each puzzle grants one star. Good luck!
;; The jungle must be too overgrown and difficult to
;; navigate in vehicles or access from the air; the Elves'
;; expedition traditionally goes on foot. As your boats
;; approach land, the Elves begin taking inventory of their
;; supplies. One important consideration is food - in
;; particular, the number of Calories each Elf is carrying
;; (your puzzle input).
;; The Elves take turns writing down the number of Calories
;; contained by the various meals, snacks, rations, etc.
;; that they've brought with them, one item per line. Each
;; Elf separates their own inventory from the previous Elf's
;; inventory (if any) by a blank line.
;; For example, suppose the Elves finish writing their
;; items' Calories and end up with the following list:
;; 1000
;; 2000
;; 3000
;; 4000
;; 5000
;; 6000
;; 7000
;; 8000
;; 9000
;; 10000
;; This list represents the Calories of the food carried by
;; five Elves:
;; The first Elf is carrying food with 1000, 2000, and
;; 3000 Calories, a total of 6000 Calories.
;; The second Elf is carrying one food item with 4000
;; Calories.
;; The third Elf is carrying food with 5000 and 6000
;; Calories, a total of 11000 Calories.
;; The fourth Elf is carrying food with 7000, 8000, and
;; 9000 Calories, a total of 24000 Calories.
;; The fifth Elf is carrying one food item with 10000
;; Calories.
;; In case the Elves get hungry and need extra snacks, they
;; need to know which Elf to ask: they'd like to know how
;; many Calories are being carried by the Elf carrying the
;; most Calories. In the example above, this is 24000
;; (carried by the fourth Elf).
;; Find the Elf carrying the most Calories. How many total
;; Calories is that Elf carrying?
;; By the time you calculate the answer to the Elves'
;; question, they've already realized that the Elf carrying
;; the most Calories of food might eventually run out of
;; snacks.
;; To avoid this unacceptable situation, the Elves would
;; instead like to know the total Calories carried by the
;; top three Elves carrying the most Calories. That way,
;; even if one of those Elves runs out of snacks, they still
;; have two backups.
;; In the example above, the top three Elves are the fourth
;; Elf (with 24000 Calories), then the third Elf (with 11000
;; Calories), then the fifth Elf (with 10000 Calories). The
;; sum of the Calories carried by these three elves is
;; 45000.
;; Find the top three Elves carrying the most Calories. How
;; many Calories are those Elves carrying in total?
