import java.util.Arrays;
import java.util.Scanner;

public class Main {
	public static void main(String[] args) throws Exception {
		new Main().run();
	}

	final long MOD = (long) (1e9 + 7);

	public void run() throws Exception {
		Scanner sc = new Scanner(System.in);
		double r = sc.nextDouble();
		double d = sc.nextDouble();
		System.out.println(Math.sqrt(d * d - r * r));
	}

	void tr(Object... objects) {
		System.out.println(Arrays.deepToString(objects));
	}
}