Помогите с задачкой, пожалуйста. (С++)

#include <cstdlib>
#include <ctime>
#include <string>
#include <sstream>
#include <fstream>
#include <iterator>
#include <iostream>
#include <vector>
#include <algorithm>
#include <map>
#include <set>
 
class Serializable {
 public:
  virtual std::ostream &serialize(std::ostream &stream) const = 0;
};
 
class Deserializable {
 public:
  virtual std::istream &deserialize(std::istream &stream) = 0;
};
 
std::ostream &operator<<(std::ostream &stream, const Serializable &object) {
  return object.serialize(stream);
}
 
std::istream &operator>>(std::istream &stream, Deserializable &object) {
  return object.deserialize(stream);
}
 
class Record : public Serializable, public Deserializable {
 public:
  Record() : name_(), address_(), phone_() {}
  explicit Record(std::istream &stream) { deserialize(stream); }
  Record(const std::string &name, const std::string &address, size_t phone)
    : name_(name), address_(address), phone_(phone) {}
  const std::string getName() const { return name_; }
  const std::string getAddress() const { return address_; }
  const size_t getPhone() const { return phone_; }
  virtual std::ostream &serialize(std::ostream &stream) const {
    return stream << getName() << ';' << getAddress() << ';' <<
      getPhone() << ';';
  }
  virtual std::istream &deserialize(std::istream &stream) {
    getline(stream, name_, ';');
    getline(stream, address_, ';');
    std::string buffer;
    getline(stream, buffer, ';');
    std::stringstream sstream(buffer);
    sstream >> phone_;
    return stream;
  }
 private:
  std::string name_;
  std::string address_;
  size_t phone_;
};
 
void createSomeRecords(const std::string &filename) {
  std::vector<Record> records;
 
  for (int i = 0; i < 10000; ++i)
    records.push_back(Record("Name", "Address",
      (rand() % 4 + 1) * 1000000 + rand() % 10000));
 
  std::ofstream outfile(filename.c_str());
  std::copy(records.begin(), records.end(),
    std::ostream_iterator<Record>(outfile));
}
 
int main(int argc, char *argv[]) {
  srand(time(NULL));
  const std::string filename = "tutor0090.txt";
 
  // создадим несколько случайных записей
  createSomeRecords(filename);
  
  std::vector<Record> records;
  std::ifstream infile(filename.c_str());
 
  // прочитаем записи из файла
  std::copy(std::istream_iterator<Record>(infile), 
    std::istream_iterator<Record>(), std::back_inserter(records));
 
  // составим карту телефонов по "атс".
  std::map<size_t, std::set<size_t> > phoneNumbers;
  for (std::vector<Record>::iterator i = records.begin();
    i != records.end(); ++i)
    phoneNumbers[i->getPhone() / 10000].insert(i->getPhone() % 10000);
 
  // посчитаем количество номеров для каждой "атс" и процент занятых
  for (std::map<size_t, std::set<size_t> >::iterator i = phoneNumbers.begin();
    i != phoneNumbers.end(); ++i)
    std::cout << "ATS " << i->first << ". " << i->second.size() <<
      " numbers, " << i->second.size() / 100 << "%" << std::endl;
}