public abstract class Vehicle
public int Wheels { get; set; }
public Vehicle(int n) { Wheels = n; }
public abstract int GetSpeed();
public int Wagons { get; set; }
interface PeopleTransport
public class Subway : Train, PeopleTransport
public int People { get; set; }
public int GetPeople() { return People; }
public class Car : Vehicle, PeopleTransport
public int People { get; set; }
public int GetPeople() { return People; }
public Car (int n) : base(n)
public override int GetSpeed() { return 100; }
public static void Main()