main(a){float b,c,h,f,u;for(;scanf("%d%f",&a,&b)+1;printf("%.0f\n",round(4*a*f)))for(h=1.5708,c=1,f=0,u=2;u<=99*a/b;u+=2)f+=c*h,h*=1-1/u,c*=(u-3)/u*(1-b*b/a/a);}