#!/usr/bin/python3

def compare(file1, file2):
	diff = False
	line = 1;
	while True:
		line1 = file1.readline()
		line2 = file2.readline()
		if line1 != line2:
			print("%d" % line)
			print(line1, end='')
			print(line2, end='')
			diff = True

		if not line1 and not line2:
			break;

		line += 1
	
	return diff;


if __name__ == '__main__':
	import sys

	if len(sys.argv) < 3:
		print("usage: lcmp file1 file2")
		sys.exit(1)

	with open(sys.argv[1], "rt") as f1, open(sys.argv[2], "rt") as f2:
		if compare(f1, f2):
			sys.exit(1)
		else:
			sys.exit(0)