"""
--- Part Two ---

As you finish identifying the misplaced items, the Elves come to you
with another issue.

For safety, the Elves are divided into groups of three. Every Elf
carries a badge that identifies their group. For efficiency, within
each group of three Elves, the badge is the only item type carried by
all three Elves. That is, if a group's badge is item type B, then all
three Elves will have item type B somewhere in their rucksack, and at
most two of the Elves will be carrying any other item type.

The problem is that someone forgot to put this year's updated
authenticity sticker on the badges. All of the badges need to be pulled
out of the rucksacks so the new authenticity stickers can be attached.

Additionally, nobody wrote down which item type corresponds to each
group's badges. The only way to tell which item type is the right one
is by finding the one item type that is common between all three Elves
in each group.

Every set of three lines in your list corresponds to a single group,
but each group can have a different badge item type. So, in the above
example, the first group's rucksacks are the first three lines:

vJrwpWtwJgWrhcsFMMfFFhFp
jqHRNqRjqzjGDLGLrsFMfFZSrLrFZsSL
PmmdzqPrVvPwwTWBwg

And the second group's rucksacks are the next three lines:

wMqvLMZHhHMvwLHjbvcjnnSBnvTQFn
ttgJtRGJQctTZtZT
CrZsJsPPZsGzwwsLwLmpwMDw

In the first group, the only item type that appears in all three
rucksacks is lowercase r; this must be their badges. In the second
group, their badge item type must be Z.

Priorities for these items must still be found to organize the sticker
attachment efforts: here, they are 18 (r) for the first group and 52
(Z) for the second group. The sum of these is 70.

Find the item type that corresponds to the badges of each three-Elf
group. What is the sum of the priorities of those item types?
"""
import string


def main():
    total_priority = 0
    priority_index = f"{string.ascii_lowercase}{string.ascii_uppercase}"

    with open("input.txt", "r", encoding="utf-8") as f:
        group = []

        for line in f:
            line_contents = line.strip()
            if not line_contents:
                continue

            group.append(line_contents)

            if len(group) == 3:
                common_item = set(group[0]).intersection(set(group[1])).intersection(set(group[2])).pop()
                common_item_priority = priority_index.index(common_item) + 1
                total_priority += common_item_priority
                group = []

    print(f"Total group priority is {total_priority}")


if __name__ == "__main__":
    main()