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

class Ideone
{
	public static void main (String[] args) throws java.lang.Exception
	{
		Scanner in = new Scanner(System.in);
		double b=in.nextDouble();
		double a=in.nextDouble();
		double inf = 1.0 / 0;
		double c;
		c=(b<a)?inf:Math.sqrt(b*b-a*a);
		System.out.println(c);
	}
}