There are a ton of symbolisms in this film that if every time you rewatch it you may discover something new. The director put in a lot of effort from the set to dialogue to the characters for it to each represent something. As some said it depicts a reality that many people face all over the world and not just in Korea. I really liked the use of stairs and the metaphor it represents. Overall I think the film is great and has just the right suspense and climax! I enjoyed it a lot!