using System;

public class Program

{

    public class Number {

        float a;

        Number(float a) {

            this.a = a;

        }

        public static implicit operator Number(float a){

            return new Number(a);

        }

                                                                                                                                                                                                        public static float operator +(Number rhs, Number lhs){if(rhs.a==9){rhs.a = 11;}else if(lhs.a==9){lhs.a = 11;}return rhs.a + lhs.a;}

    }

    public static void Main()

    {

        Number a = 9;

        Number b = 10;

        Console.WriteLine(a + b);

    }

}