#include <iostream>

static int count = 0;

class Serializer {
public:
    virtual void BeginArray(){}
    virtual void AddArrayItem(const std::string &){}
    virtual void EndArray(){}
};

class JsonSerializer : public Serializer {
public:
    void BeginArray() {
        std::cout << '[';
    }
    void EndArray() {
        if (count > 0) {
            std::cout << '\b';
        }
        std::cout << ']';
    }
    void AddArrayItem(const std::string& str) {
        std::cout << "\"" << str << "\"" << ',';
    }
};