class Stopwatch{

    private long time=0;

    public void Start(){

        if (time==0){
            this.time = System.nanoTime();
        }
    }

    public void Stop(){
        long currentTime=System.nanoTime();
        System.out.println(currentTime-this.time);
//        System.out.println(this.time);
//        System.out.println(currentTime);
        this.time=0;
    }
}



public class Main {


    public static void main(String[] args) {
        // write your code here

Stopwatch stoperica = new Stopwatch();

stoperica.Start();



stoperica.Stop();


    }
}