program ideone;

var
x, eps: real;
i: integer;
res, s: real;

begin
    readln(x, eps);

    res := 0;
    s := x;
    i := 1;

    while abs(s) > eps do
    begin
        res := res + s;
        s := s * Sqr(x) / ((i + 1) * (i + 2));
        i := i + 2;
    end;

    writeln(res);
end.