var x: real;

function f(x: real): real;

begin

   if x < 0 then f:= ln(x)/(1 - x)

   else if (0 <= x) and (x < pi) then f:= 10

   else if (pi <= x) then f:= cos(6 * x);

end;

begin

   readln(x);

   writeln(f(x));

end.