#include <iostream>
#include "sales_item.hpp"
int main() {
	Sales_item total; // variable to hold data for the next transaction
	// read the first transaction and ensure that there are data to process
	if (std::cin >> total) {
		Sales_item trans; // variable to hold the running sum
		// read and process the remaining transactions
		while (std::cin >> trans) {
			// if we’re still processing the same book
			if (total.isbn() == trans.isbn())
				total += trans; // update the running total
			else {
				// print results for the previous book
				std::cout << total << std::endl;
				total = trans; // total now refers to the next book
			}
		}
		std::cout << total << std::endl; // print the last transaction
	} else {
		// no input! warn the user
		std::cerr << "No data?!" << std::endl;
		return -1; // indicate failure
	}
	return 0;
}