#include <iostream>
#include <thread>

//thread_local int var;
//int var;

class A{
    public:

    void fun () {
        for(int i=0; i<10; i++){
            var = var+i;
        }
        std::cout<<"var = "<<var<<std::endl;
    }
};

int main() {
    A a, b, c;
    std::thread t1(&A::fun, &a);
    std::thread t2(&A::fun, &b);
    std::thread t3(&A::fun, &c);

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

    return 0;
}