program tju1105;
const
  zero=1e-6;
var
  a,k,l,r,t,s1,s2:extended;
begin
  repeat
    read(a,k);
    l:=k;r:=1e10;
    repeat
      t:=(l+r)/2;
      s1:=a*t*t/2;
      s2:=(t-k)*(t-k)*(t-k)/3;
      if abs(s1-s2)<zero then break else if s1>s2 then l:=t else r:=t;
    until false;
    writeln(t:0:4);
  until seekeof;
end.