Read /input/dataset/dataset.yaml and /input/dataset/mock/prices-mock.csv.

Write a Python script to /output/sum_prices.py.

Requirements:
- The script must read a CSV with columns date,symbol,price.
- It must sum the price column exactly.
- It must print only the final numeric total.
- Use Python 3 standard library only.
- Do not modify any other files.
