import re


def parse_password(password_str):
    """
    Given a password string, return a dictionary
    "1-3 a: abcde" => "{low}-{high} {letter}: {password}"
    """
    match = re.search("(.*)-(.*) (.): (.*)", password_str)

    if not match:
        return None

    return {
        "low": int(match.group(1)),
        "high": int(match.group(2)),
        "letter": match.group(3),
        "password": match.group(4),
    }