import java.util.Scanner;

public class Main {
	public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
		double h = sc.nextDouble();
		double r = sc.nextDouble();
		sc.close();

		System.out.println(h * r * 30574.154032453271139 / 912.70 / 548.36);
	}
}