#!/usr/bin/env python


def compute_seat_pos(code, code_lower, code_upper, pos_max):
	pos_min = 0
	for i in code:
		if i ==  code_lower:
			pos_max = int((pos_min + pos_max-1)/2)
			continue
		if i ==  code_upper:
			pos_min = int((pos_min + pos_max+1)/2)
			continue
	return pos_min


seats = []
with open("input01.txt","r") as f:
	for line in f:
		line = line.strip()
		seats.append(compute_seat_pos(line[:7], "F", "B", 127) * 8 + compute_seat_pos(line[-3:], "L", "R", 7)) 

print(max(seats))