import java.util.Scanner;

public class Main {

	@SuppressWarnings("resource")
	public static void main(String args[]) {
		Scanner scanner = new Scanner(System.in);
		double r = scanner.nextDouble();
		double d = scanner.nextDouble();
		
		double X=d*d-r*r;
		
		System.out.println(Math.sqrt(X));
	}
}