import sys

def load_words(filename):
	words = []
	with open(filename, "r") as f:
		for line in f:
			words.append(line[:-1])
	return words

# PART 1

def has_n_chars(word, n):
	count = {}
	for char in word:
		count[char] = count.get(char, 0) + 1
	return n in count.values()

def count_words(words):
	twice = 0
	thrice = 0
	for word in words:
		if has_n_chars(word, 2):
			twice += 1
		if has_n_chars(word, 3):
			thrice += 1
	return twice, thrice

def checksum(words):
	twice, thrice = count_words(words)
	return twice * thrice

# PART 2

def differ_by(a, b):
	count = 0
	for x, y in zip(a, b):
		if x != y:
			count += 1
	return count

def find_ids(words):
	for i, a in enumerate(words):
		for b in words[i:]:
			if differ_by(a, b) == 1:
				return a, b

def common_chars(a, b):
	result = []
	for x, y in zip(a, b):
		if x == y:
			result.append(x)
	return "".join(result)

def main(filename):
	words = load_words(filename)
	print(f"Solutions for {filename}")
	print(f"Part 1: {checksum(words)}")
	a, b = find_ids(words)
	print(f"Part 2: {common_chars(a, b)}")

if __name__ == "__main__":
	for filename in sys.argv[1:]:
		main(filename)