I would like to create a script to write full books using chat gpt
I got the following script, but I want longer content (output). How can I force it?

from openai import OpenAI

model = "gpt-3.5-turbo"
client = OpenAI(api_key='...')

with open('sysprompt') as f:
    sysprompt = f.read()

with open('index') as f:
    index = f.read()

conversation = [{
    "role": "system",
    "content": sysprompt
}]

out = ""
chapters = index.split('-')
i = 1
for c in chapters:
    conversation.append({
        "role": "user",
        "content": f"nWrite the content for: {c}"
    })
    response = client.chat.completions.create(model=model, messages=conversation)
    out += response.choices[0].message.content + "n"
    print(f"Wrote: {i}/{len(chapters)}")
    i += 1

with open('out.txt', 'w') as f:
    f.write(out)

In sysprompt there is the prompt to write a story book
In index there is the list of chapters (37) for the book

I tryed with the code above but I want longer output