start = std::chrono::system_clock::now();
newItem.shiftAndSubstract();
end = std::chrono::system_clock::now();
elapsed_seconds = end - start;
end_time = std::chrono::system_clock::to_time_t(end);
std::cout << "finished computation at " << std::ctime(&end_time)
<< "elapsed time: " << elapsed_seconds.count() << "s\n";
newItem.myPause();