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


class Main {
	public static void main(String[] args) {
		Scanner in = new Scanner(System.in);
		PrintWriter out = new PrintWriter(System.out);
		float x = in.nextFloat();
		float y = in.nextFloat();
		float a=x*x+y*y;
		if((y<0)||(a>1)||((x>0)&&(a<0.3))){
			System.out.println(Math.sqrt(Math.abs(x-1)));
		}
		else{
			System.out.println(x*x-1);
		}
	}
}