import math

def get(s, l, u, ltok, utok):
	if l == u:
		return l

	c = s[:1]
	h = math.ceil((u - l) / 2)
	assert c in (ltok, utok)
	if c == ltok:
		return get(s[1:], l, u - h, ltok, utok)
	return get(s[1:], l + h, u, ltok, utok)


def seat(s):
	row = get(s[:7], 0, 127, "F", "B")
	col = get(s[7:10], 0, 7, "L", "R")
	return row, col


def seat_id(row, col):
	return row * 8 + col


def missing_seat(seats):
	a = sorted(seats)
	b = range(a[0], a[-1])
	missing = set(b) - set(a)
	assert len(missing) == 1
	return missing.pop()


assert seat("FBFBBFFRLR") == (44, 5)

assert seat("BFFFBBFRRR") == (70, 7)
assert seat_id(70, 7) == 567
assert seat("FFFBBBFRRR") == (14, 7)
assert seat_id(14, 7) == 119
assert seat("BBFFBBFRLL") == (102, 4)
assert seat_id(102, 4) == 820

assert seat("BBFBFBFLLL") == (106, 0)


with open("data.txt", "r", encoding="utf-8") as f:
	lines = f.readlines()

seats = [seat_id(*seat(x.rstrip())) for x in lines]
sid_max = max(seats)

print(f"Highest seat ID: {sid_max}")
print(f"Your seat is   : {missing_seat(seats)}")