#!/usr/bin/env python3
import re
from collections import Counter
from itertools import groupby
from operator import itemgetter

lines = (x.strip() for x in open("input.txt"))
first = next(lines)
next(lines)

repl = (re.match(r"([A-Z]{2}) -> ([A-Z])", line).groups() for line in lines)
repl = (v for (a, b), m in repl for v in [(a+m, a+b), (m+b, a+b)])
repl = {k: list(map(itemgetter(1), v)) for k, v in groupby(sorted(repl), itemgetter(0))}

combinations = Counter(first[i:i+2] for i in range(len(first)-1))
for _ in range(40):
    combinations = {k: sum_val for k, v in repl.items() if (sum_val := sum(combinations.get(x, 0) for x in v)) > 0}

letters = {k: sum(map(itemgetter(1), v)) for k, v in groupby(sorted(combinations.items()), lambda x: x[0][0])}
letters[first[-1]] += 1

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