def days_of_month(month):
    """Returns the day of a month"""    
    month_lookup = {"Jan": 31, "Feb": 28, "Mar": 31, "Apr":30, "May":31, "Jun":30, "Jul":31,
             "Aug": 31, "Sep": 30, "Oct": 31, "Nov":30, "Dec": 31}
    return month_lookup[month]