//第二章最后一道习题,暂未学习class
#include <iostream>
#include<string>

struct Sale_data {    //Sale_date为一个类体,在里面定义了若干数据成员
                      //数据成员定义了对象的具体内容,每个对象有自己的一份数据成员的拷贝
    std::string ISBN;
    unsigned booksum = 0;
    double money = 0.00;
};
unsigned cnt = 0;
double total = 0.00;
Sale_data data1, data2;
int main() {
    while(std::cin>>data1,data2)
    if (data1.ISBN == data2.ISBN) {
        unsigned Cnt = data1.booksum + data2.booksum;
        double total = data1.money + data2.money;
        std::cout << data1.ISBN << "总销量: " << cnt << " 总金额: " << total << std::endl;
        if (cnt != 0)
            std::cout << "平均单价: " << total / cnt << std::endl;
        else
            std::cout << "没有销售记录" << std::endl;
        return 0;
    }
    else {
        std::cerr << "ISBN必须一致." << std::endl;
        return -1;
    }



}