const {! return a1.city < a2.city;! }! };! ! void add_karma_to_novosibirsk_people(! vector<pair<Address, Person> > people_and_addresses) {! typedef multimap<Address, Person, CityCompare> AdrMap;! ! AdrMap addresses_by_city;! ! for (int i = 0; i < people_and_addresses.size(); ++i)! addresses_by_city.insert(people_and_addresses[i]);! ! pair<AdrMap::const_iterator, AdrMap::const_iterator> nsk_range =! addresses_by_city.equal_range(Address("Novosibirsk"));! ! // Yay, Novosibirsk people!!! for (AdrMap::const_iterator it = nsk_range.first;! it != nsk_range.second; ++it)! !add_karma(it->second, 100);! }!