Разработать класс, инкапсулирующий банковский счет

#include <string>
#include <iostream>
#include <stdexcept>
 
class Account {
 public:
  static const unsigned long int MAXIMUM_DEPOSIT;
  Account(int accountId, const std::string &ownerName,
    const std::string &currencyName, long int balance)
    : accountId(accountId), ownerName(ownerName),
    currencyName(currencyName), balance(balance) {}
  int getAccountId() const { return accountId; }
  const std::string &getOwnerName() const { return ownerName; }
  const std::string &getCurrencyName() const { return currencyName; }
  unsigned long int getBalance() const { return balance; }
  void withdraw(unsigned int amount) {
    if (balance < amount) {
      throw std::runtime_error("not enough equity on account");
    }
    balance -= amount;
  }
  void deposit(unsigned int amount) {
    if (balance + amount < balance) {
      throw std::overflow_error("adding amount to balance overflows maximum balance");
    }
    balance += amount;
  }
 private:
  int accountId;
  std::string ownerName;
  std::string currencyName;
  unsigned long int balance;
};
 
const unsigned long int Account::MAXIMUM_DEPOSIT = -1;
 
std::ostream &operator<<(std::ostream &stream, const Account &account) {
  return stream << "Accout{" <<
    "accountId=" << account.getAccountId() << "," <<
    "ownerName='" << account.getOwnerName() << "'," <<
    "currencyName='" << account.getCurrencyName() << "'," <<
    "balance=" << account.getBalance() << "}";
};
 
 
int main(int argc, char *argv[]) {
  
  Account a(1, "SOMEONE RICH", "USD", 50);
  
  std::cout << a.getOwnerName() << " has " << a.getBalance() << " " <<
    a.getCurrencyName() << " on account." << std::endl;
  
  // попытка положить на счет
  unsigned int amount = 1000;
  try {
    a.deposit(amount);
    std::cout << a.getOwnerName() << " deposited " << amount << " " <<
      a.getCurrencyName() << std::endl;
  } catch (std::exception &e) {
    std::cout << a.getOwnerName() << " could not deposit " << amount <<
      " " << a.getCurrencyName() << ": " << e.what() << std::endl;    
  }
  std::cout << a.getOwnerName() << " has " << a.getBalance() << " " <<
    a.getCurrencyName() << " on account." << std::endl;
 
  // попытка снять немного со счета
  amount = 100;
  try {
    a.withdraw(amount);
    std::cout << a.getOwnerName() << " withdrawn " << amount << " " <<
      a.getCurrencyName() << std::endl;
  } catch (std::exception &e) {
    std::cout << a.getOwnerName() << " could not withdraw " << amount <<
      " " << a.getCurrencyName() << ": " << e.what() << std::endl;    
  }
  std::cout << a.getOwnerName() << " has " << a.getBalance() << " " <<
    a.getCurrencyName() << " on account." << std::endl;
 
  // попытка снять слишком много со счета
  amount = 100000;
  try {
    a.withdraw(amount);
    std::cout << a.getOwnerName() << " withdrawn " << amount << " " <<
      a.getCurrencyName() << std::endl;
  } catch (std::exception &e) {
    std::cout << a.getOwnerName() << " could not withdraw " << amount <<
      " " << a.getCurrencyName() << ": " << e.what() << std::endl;    
  }
  std::cout << a.getOwnerName() << " has " << a.getBalance() << " " <<
    a.getCurrencyName() << " on account." << std::endl;
 
  return 0;
};