from itertools import groupby
from math import prod
from pathlib import Path

FILE = "input.txt"


def main(file: str = FILE) -> int:
    *value_rows, operator_row = Path(file).read_text().splitlines()
    operators = operator_row.split()

    # Columns represent vertical numbers; blank columns separate problems.
    columns = ("".join(col).strip() for col in zip(*value_rows))
    operands = (
        [int(n) for n in group]
        for is_value, group in groupby(columns, key=bool)
        if is_value
    )

    return sum(compute(vals, op) for vals, op in zip(operands, operators))


def compute(vals: list[int], op: str) -> int:
    ops = {"+": sum, "*": prod}
    try:
        return ops[op](vals)
    except KeyError:
        raise ValueError(f"unknown operator: {op}")


if __name__ == "__main__":
    print(main())