//pascal

uses Math;

var

x, y : real;

begin

readln(x);

if (x >= 4) then

   y := sqrt(power(x, 3) + 3 * power(x, 2) + 7.3)

else if (x > 2) and (x < 4) then

   y := cos(2*x) - 1.5

else if (x <= 2) then

   y := 5 * power(x, 2) -3;

writeln(y:5:2);

end.