---

public interface IHealable
{
    void Heal(int amount);
}

public class Player : IHealable
{
    protected int health;

    public int Health
    {
        get { return health; }
        set
        {
            if (value >= 100)
                health = 100;
            else if (value <= 0)
                health = 0;
            else
                health = value;
        }
    }

    public Player(int health)
    {
        this.health = health;
    }

    public void Heal(int amount)
    {
        Health = health + amount;
    }   
}

Player player = new Player(50);

player.Heal(30);