import java.io.FileInputStream;
import java.io.InputStreamReader;
import java.io.StreamTokenizer;


public class cylinder {
	public static void main(String[] args) throws Exception {
		StreamTokenizer st = new StreamTokenizer(new InputStreamReader(new FileInputStream("cylinder.in")));
		double w = 1.0, h=1.0;
		while(true) {
			st.nextToken();
			w = st.nval;
			st.nextToken();
			h = st.nval;
			if(w == 0.0 || h == 0.0) break;
			long val = Math.round(1000.0 * calc(w,h));
			double x = val / 1000.0;
			System.out.println(x);
		}
	}
	
	public static double calc(double w, double h) {
		double r1=0.0, r2=0.0, r3=0.0;
		if(w<=((h-w)/Math.PI)) {
			double r = w / 2.0;
			r1 = (Math.PI * r * r) * w;
			//System.out.println("r1: " + r1);
		}
		double x = w/Math.PI;
		double r = x / 2.0;
		if(h-x>0.0) {
			r2 = (Math.PI * r * r) * (h-x);
			//System.out.println("r2: " + r2);
		}
		x = h/(Math.PI+1.0);
		r = x/ 2.0;
		if(w>=(h-x)/Math.PI) {
			r3 = (Math.PI * r * r) * w;
			//System.out.println("r3: " + r3);
		}
		return Math.max(r1, Math.max(r2,r3));
	}

}