using System;

public class Program

{

    public static void Main()

    {

        NrInt v0= new NrInt(3);

    NrInt v1= new NrInt(4);

    NrInt v2= new NrInt(5);

    NrInt s0= v0+v1+v2;

    }

}

​

public class NrInt{

    public NrInt(int nr) { Nr =nr;}

    public int Nr { get; set;}

    public static NrInt operator +(NrInt a, NrInt b){

    int c = a.Nr + b.Nr;

    System.Console.WriteLine("x+y={0}+{1}={2}", a.Nr, b.Nr, c);

    return new NrInt(c);

    }

}