import java.util.*;
import java.lang.*;
import java.io.*;

class Main
{
	public static void main (String[] args) throws java.lang.Exception
	{
		Scanner in = new Scanner(System.in);
		double n = in.nextDouble();
		double length = Math.floor(Math.sqrt(n));
		double width = Math.ceil(n / length);
		double k = 2 * n + length + width;
		System.out.print((int)(k));
	}
}