Can anyone tell me how much % of the live action version follows the novel - did it adapt it well?.....please let me know in your reply....thanks

also did season 1 and 2 adapt the whole novel or were they changes and cuts

basically i want to know if i watch the show would i need to read the novel to understand anything or does the show expand on the novels story making it so if you watch it you are satisfied because it tells the novels story and also expands on it......i look forward to your answer

thanks