uniquecitysales

import os

import sys
from iso8601 import iso8601

sales = {}

try:
    filename = input()
    if not os.path.isfile(filename) or not os.access(filename, os.R_OK):
        raise ValueError()

    with open(filename, 'r', encoding='utf8') as f:
        for line in f:
            if line.strip() == "":
                continue
            split = line.split(",")
            if len(split) != 5:
                raise ValueError()
            idf = split[0].replace('"', "")
            country = split[1]
            city = split[2].replace('"', "")
            dt = split[3].replace('"', "")
            price = float(split[4])
            dtparse = iso8601.parse_date(dt)
            if city not in sales:
                sales[city] = set()
            sales[city].add(idf)

    if not sales:
        raise ValueError()

    result = {}
    for city, ids in sales.items():
        newids = set()
        for city1, ids1 in sales.items():
            if city == city1:
                continue
            newids |= ids1

        for idx in ids:
            if idx not in newids:
                if city not in result:
                    result[city] = set()
                result[city].add(idx)

    if not result:
        print("NO UNIQUE SALES")
        sys.exit()

    for key in sorted(result):
        sortedIds = result[key]
        if len(sortedIds) > 1:
            sortedIds = sorted(sortedIds)
        print("{},{}".format(key, ",".join(sortedIds)))
except Exception as e:
    print("INVALID INPUT")