#include <stdio.h>
#include <assert.h>
#include <math.h>
#define SWAP(a,b) (a)=(a)^(b); (b)=(a)^(b); (a)=(a)^(c);
#define MAX(a,b) (a)>(b)?(a):(b)
#define MIN(a,b) (a)<(b)?(a):(b)
#define PI 3.14159265358979323846
#define D 0
int main(){
	int b,a;
	freopen("cylinder.in","r",stdin);
	double r1,r2,V1,V2,h1,h2;
	while(1){
		assert(2==scanf("%d %d",&a,&b));
		if(D)fprintf(stderr,"got: %d, %d\n",a,b);
		if(!a && !b) return 0;
		assert(a<=b);
		//fall 1:	
		r1=a/(2.*PI);
		r1=MIN(r1,a/2.)	;
		h1=(double)b -2*r1;
		V1=PI*r1*r1*h1;
		//Fall 2:
		r2=((double)b)/(2*PI+2);
		r2=MIN(a/2.,r2);
		h2=a;
		V2=PI*r2*r2*h2;
		printf("%.3f\n",MAX(V1,V2));
	}
	return 0;
}