with open("i19.txt", "r") as f:
    data = f.read()

eqs = []
molecule = ""
for line in data.splitlines():
    if "=>" in line:
        lhs, rhs = line.split(" => ")
        eqs.append((lhs, rhs))
    elif line:
        molecule = line.strip()

molecules = set()
for lhs, rhs in eqs:
    for i in range(len(molecule)):
        f, t = molecule[:i], molecule[i:]
        if t.startswith(lhs):
            n = f + t.replace(lhs, rhs, 1)
            molecules.add(n)
print(len(molecules))


# It seems like the problem input is specifically designed so that reversing
# the molecule back to 'e' works by simply replacing RHS with LHS continuously.
# Intuitively, it seems like this should not work in many cases or at least not
# result in the shortest sequence. Probably I am just salty that it took me so
# long to find this trivial solution.
x = molecule
count = 0
while len(x) > 1:
    old_len = len(x)
    for lhs, rhs in eqs:
        if rhs in x:
            x = x.replace(rhs, lhs, 1)
            count += 1
            break
    else:
        break

assert x == 'e'
print(count)