public static void Main()
Console.WriteLine(Math.PI);
Console.WriteLine(Math.Abs(-5.5));
Console.WriteLine(Math.Ceiling(3.78));
Console.WriteLine(Math.Floor(2.55));
Console.WriteLine(Math.Max(3,7));
Console.WriteLine(Math.Min(3,-3));
Console.WriteLine(Math.Sqrt(7.7));
Console.WriteLine(Math.Pow(2.2,3));
Console.WriteLine(Math.Round(3.5678,2));
Console.WriteLine("Въведи радиус:");
rad=double.Parse(Console.ReadLine());
double s=Math.PI*rad*rad;
Console.WriteLine("Лице={0}",s);
Console.WriteLine("Периметър={0}",p);