#include <iostream>
#include <thread>
#include <shared_mutex>
//#include <unique_lock>
using namespace std;
int sharedresource=0;
shared_mutex shmtx;

void reader(int id)
{
    shared_lock<shared_mutex> lock(shmtx);
    cout<<"The variable is "<<sharedresource<<" of id"<<id<<endl;
}

void writer(int id)
{
    unique_lock<shared_mutex> lock(shmtx);
    sharedresource++;
    cout<<"The id is "<<id<<endl;
}

int main() {

    thread twriter[] = {thread(writer,1),thread(writer,2),thread(writer,3)};
    thread treader[] = {thread(reader,1),thread(reader,2),thread(reader,3),thread(reader,4)};

    for(auto t1:twriter) t1.join();
    for(auto t2:treader) t2.join();
    
    
    std::cout << "Hello world!" << std::endl;
    return 0;
}