#include <chrono>

class stopwatch
{
    std::chrono::time_point<std::chrono::high_resolution_clock> last_;
public:
    stopwatch()
    {
        reset();
    }
    void reset()
    {
        last_ = std::chrono::high_resolution_clock::now();
    }
    std::chrono::microseconds elapsed() const
    {
        auto t = std::chrono::high_resolution_clock::now();
        return std::chrono::duration_cast<std::chrono::microseconds>(t - last_);
    }
    std::chrono::microseconds tick()
    {
        auto t = std::chrono::high_resolution_clock::now();
        auto elapsed = std::chrono::duration_cast<std::chrono::microseconds>(t - last_);
        last_ = t;
        return elapsed;
    }
};