from datetime import datetime


def parse_date_only(iso: str) -> datetime:
    """
    Parse date faster.

    Preconditions:
        - iso starts with the format of "YYYY-MM-DD" (e.g. "2021-10-20" or "2021-10-20T10:04:14")
        - iso is a valid date (this function does not check for the validity of the input)

    :param iso: Input date
    :return: Datetime object
    """
    return datetime(int(iso[:4]), int(iso[5:7]), int(iso[8:10]))