#!/usr/bin/env python

import re
from collections import defaultdict

RE_INS = re.compile("(.*)\s+->\s+(.*)$")

def tokenize_polymer(polymer):
	result = defaultdict(int)
	for i in range(0, len(polymer)-1):
		k = polymer[i:i+2]
		result[k] += 1	
	return result

def iterate_polymer(polymer, rules):
	delta = defaultdict(int)
	pairs = list(polymer.keys())
	for pair in pairs:
		if pair not in rules:
			continue
		if polymer[pair] == 0:
			continue
		p1 = pair[0]+rules[pair]
		p2 = rules[pair]+pair[1]
		delta[p1] += polymer[pair]
		delta[p2] += polymer[pair]
		delta[pair] -= polymer[pair]
	for pair in delta:
		polymer[pair] += delta[pair]
	return polymer

polymer = None
rules = dict()
polymer_pairs = defaultdict(int)

with open("input01.txt","r") as f:
	polymer = f. readline().strip()

	for line in f:
		line = line.strip()
		if len(line) == 0:
			continue
		m = RE_INS.match(line)
		if not m:
			print(line)
		rules[m.group(1)] = m.group(2)
for i in range(0, len(polymer)-1):
	k = polymer[i:i+2]
	polymer_pairs[k] += 1	

polymer_pairs = tokenize_polymer(polymer)
for i in range(40):
	polymer_pairs = iterate_polymer(polymer_pairs, rules)
#	print(polymer_pairs)

sums = defaultdict(int)
for i in polymer_pairs.keys():
	sums[i[1]] += polymer_pairs[i]
sums[polymer[0]] += 1

p_max = max([x for x in sums.values()])
p_min = min([x for x in sums.values()])
print(p_max - p_min)