static void Main(string[] args) { Aircompany airCompany = new Aircompany(); Airliner carrier = new Airliner() {Name="a1", range=20000, fuelConsumption=100, capacity=200}; airCompany.Add(carrier); Freighter freighter = new Freighter() { Name = "a2", range = 1000, fuelConsumption = 80, carrying = 5000 }; airCompany.Add(freighter); CombiAirplane combiAirplane = new CombiAirplane() { Name = "a3", range = 800, fuelConsumption = 70, carrying = 1000, capacity = 70 }; airCompany.Add(combiAirplane); Console.WriteLine(airCompany.maxCapacity); ICollection<IAirplane> find = airCompany.Search(75,110).ToList<IAirplane>(); foreach (var i in find) i.ShowElement(); }