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

class Main
{
	public static void main (String[] args) throws java.lang.Exception
	{
		int s, a;
		double h, dk;
		Scanner in = new Scanner(System.in);
		s = in.nextInt();
		a = in.nextInt();
		dk = Math.sqrt(a*a + 8*s);
		h = (-a + dk) / 2;
		System.out.printf("%.2f",h);
	}
}