uses crt;
var
   y, x: real;
begin
     write('x=');
     readln(x);
     if (sin(3*x)=0) or (ln(1+sqr(x))=0) or (cos(x)<=0) then
        writeln('Îøèáêà')
        else begin
             y:=2*(cos(3*x)/sin(3*x))*ln(cos(x))/ln(1+sqr(x));
             writeln('y=',y:7:4);
        end;
end.