program m1;
var
x,A,C: integer;
answer:real;
begin
read(x,A,C);
answer:=(x*x+A*x-C)/power((x*x*x - A*x), (1/3));
writeln(answer);
end.
program m1;
var
x,A,C: integer;
answer:real;
begin
read(x,A,C);
answer:=(x*x+A*x-C)/power((x*x*x - A*x), (1/3));
writeln(answer);
end.