// C# program to illustrate the interface 

using System; 

​

// interface declaration 

interface Vehicle { 

    // all are the abstract methods. 

    void changeGear(int a); 

    void speedUp(int a); 

    void applyBrakes(int a); 

} 

​

// class implements interface 

class Bicycle : Vehicle{ 

    int speed; 

    int gear; 

    // to change gear 

    public void changeGear(int newGear) 

    { 

        gear = newGear; 

    } 

    // to increase speed 

    public void speedUp(int increment) 

    { 

        speed = speed + increment; 

    } 

    // to decrease speed 

    public void applyBrakes(int decrement) 

    { 

        speed = speed - decrement; 

    } 

    public void printStates() 

    { 

        Console.WriteLine("speed: " + speed + " gear: " + gear); 

    } 

} 

​

// class implements interface 

class Bike : Vehicle { 

    int speed; 

    int gear; 

    // to change gear 

    public void changeGear(int newGear) 

    { 

        gear = newGear; 

    } 

    // to increase speed 

    public void speedUp(int increment) 

    { 

        speed = speed + increment; 

    } 

    // to decrease speed 

    public void applyBrakes(int decrement){ 

        speed = speed - decrement; 

    } 

    public void printStates() 

    { 

        Console.WriteLine("speed: " + speed + " gear: " + gear); 

    } 

} 

​

public class GFG { 

    // Main Method 

    public static void Main(String []args) 

    { 

        // creating an instance of Bicycle 

        // doing some operations 

        Bicycle bicycle = new Bicycle(); 

        bicycle.changeGear(2); 

        bicycle.speedUp(3); 

        bicycle.applyBrakes(1); 

        Console.WriteLine("Bicycle present state :"); 

        bicycle.printStates(); 

        // creating instance of bike. 

        Bike bike = new Bike(); 

        bike.changeGear(1); 

        bike.speedUp(4); 

        bike.applyBrakes(3); 

        Console.WriteLine("Bike present state :"); 

        bike.printStates(); 

    } 

}