A Real Challenge Kattis Problem Solution In Java

//Nayeem Shahriar Joy,Applied Physics & Electronic Engineering, University of Rajshahi.

 

import java.util.HashSet;

import java.util.Scanner;

import java.util.Set; 

public class Joy{

public static void main(String[] args) {

// Get input from the user w/ sentinel logic

Scanner io = new Scanner(System.in);

double a = io.nextDouble();

System.out.println(4*Math.sqrt(a));

}

}