stoper

#include <chrono>


using namespace std;
class timer

{
    chrono::time_point<chrono::high_resolution_clock> a,b;
public:
    void start(){a = chrono::high_resolution_clock::now();}
    void stop() {b = chrono::high_resolution_clock::now();}
    double value()
    {
        chrono::duration<double> elapsed_seconds = b-a;
        return elapsed_seconds.count();
    }
    void show()
    {
        cout << value()<<" s"<<endl;
    }
};



class timer_cumulative
{
    chrono::time_point<chrono::high_resolution_clock> a,b;
    double cumul_time;
    double elapsed_sec()
    {
        chrono::duration<double> elapsed_seconds = b-a;
        return elapsed_seconds.count();
    }
public:
    void reset(){cumul_time = 0;}
    timer_cumulative(){reset();}
//    void start(){a = chrono::high_resolution_clock::now(); reset();}
//    void resume() {a = chrono::high_resolution_clock::now();}
    void start(){a = chrono::high_resolution_clock::now();}
    void stop() {b = chrono::high_resolution_clock::now(); cumul_time += elapsed_sec();}
    void show()
    {
        cout << cumul_time<<" s"<<endl;
    }
};