puzzle_input = sys.stdin.read().strip()
rules = []
your_ticket = None
nearby_tickets = []
is_your_ticket = False
is_nearby_tickets = False
for line in puzzle_input.split('\n'):
if '-' in line:
# Parse a rule.
rules.append(Rule.from_string(line))
elif 'your ticket' in line:
is_your_ticket = True
elif line and is_your_ticket:
your_ticket = Ticket.from_string(line)
is_your_ticket = False
elif 'nearby tickets' in line:
is_nearby_tickets = True
elif line and is_nearby_tickets:
nearby_tickets.append(Ticket.from_string(line))
invalid_fields = []
results = {}
field_rule = [[x, y] for x in range(len(rules)) for y in range(len(rules))]
for i, ticket in enumerate(nearby_tickets):
is_valid_ticket = True
for j, num in enumerate(ticket.nums):
each_rule = [r.valid(num) for r in rules]
