""" Pair insertion """
import collections

insertion_rules = {}

with open("14_input.txt") as f:
    polymer_template = f.readline().strip()
    f.readline()

    for line in f:
        pair, insert = line.strip().split(" -> ")

        insertion_rules[pair] = insert

extended_template = []

expected_length = len(polymer_template)

for gen in range(10):
    for i in range(len(polymer_template) - 1):

        pair = polymer_template[i:i+2]
        extended_template += [
            polymer_template[i],
            insertion_rules[pair],
        ]

    polymer_template = "".join(
        extended_template + [polymer_template[i + 1]]
    )
    extended_template = []
    expected_length += expected_length - 1

    assert len(polymer_template) == expected_length, "Length unexpected"

letter_count = collections.defaultdict(int)
for letter in polymer_template:
    letter_count[letter] += 1

print(max(letter_count.values()) - min(letter_count.values()))