using System;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        Calculator.Add(1,2);

    }

}

​

public class Calculator{

    [Obsolete("Use Add(List<int> Numbers) Method")]

    public static int Add(int a, int b){

     return a + b;

    }

public static int Add(List<int> Numbers){

      int sum = 0;

    foreach(int n in Numbers){

        sum = sum + n;

    }

    return sum;

    }

}