# Profile: Data · NumPy and pandas
from io import StringIO
import pandas as pd

csv_text = "topic,minutes\n Python ,20\ndata,30\npython,25\ncharts,unknown\n"
raw = pd.read_csv(StringIO(csv_text), dtype="string", keep_default_na=False)
clean = raw.copy()
clean["topic"] = clean["topic"].str.strip().str.lower()
clean["minutes"] = pd.to_numeric(clean["minutes"], errors="coerce")
valid = clean["minutes"].notna() & clean["minutes"].ge(0)
accepted = clean.loc[valid].copy()
rejected = raw.loc[~valid].copy()
summary = accepted.groupby("topic", as_index=False)["minutes"].sum()
summary = summary.sort_values("topic")
print(summary.to_string(index=False))
print("Rejected rows:", len(rejected))
print("Accepted total:", int(accepted["minutes"].sum()))