Function t3

STL/thread.cpp:37–48

mutex m;

void t3()
{
    while (cnt > 0) {
        lock_guard<mutex> lockGuard(m);
        // m.lock();
        if (cnt > 0) {
            --cnt;
            cout << cnt << "\tt3" << endl;
        }
        // m.unlock();
    }
}

void t4()
{