#include <iostream>
#include <atomic>
#include <thread>


const int COUNT = 300;

using namespace std;

int main()
{

    atomic<bool> e1{false}, e2{false}, e3{false};

    thread t1([&]() {
        for(int i=0; i < COUNT; ++i)
        {
            bool e = true;
            while (!e1.compare_exchange_strong(e, false)) e = true;
            cout << "A" << endl;
            e2.store(true);
        }
    });

    thread t2([&]() {
        for(int i=0; i < COUNT; ++i)
        {
            bool e = true;
            while (!e2.compare_exchange_strong(e, false)) e = true;
            cout << "B" << endl;
            e3.store(true);
        }
    });

    thread t3([&]() {
        for(int i=0; i < COUNT; ++i)
        {
            bool e = true;
            while (!e3.compare_exchange_strong(e, false)) e = true;
            cout << "C" << endl;
            e1.store(true);
        }
    });

    e1.store(true);

    t1.join();
    t2.join();
    t3.join();

    return 0;
}