double x, y;
Console.Write("x=");
x = double.Parse(Console.ReadLine());
if (x > 6)
y = 5.0 / 27 * (x * x + 4 * x - 6);
else
if (x <= 0)
y = 23.0 / 7 * Math.Abs(x * x * x + 4);
else
y = Math.Log(16, 3);
Console.WriteLine("y={0}",y);