static void Main(string[] args)
{
Shape s = new Shape(1, 2);
Shape s2 = new Shape(3, 5);
Rec r = new Rec(3, 6);
Tri t = new Tri(2, 5);
List <Shape> sh = new List <Shape>();
List <int> numbs = new List <int>();
sh.Add(s);
sh.Add(s2);
//numbs.Add(s.Area());
sh.FindAll(o => o.Area() > 4);
Console.WriteLine(s.Area());
Console.WriteLine(r.Area());
Console.WriteLine(t.Area());
Console.ReadLine();
}