using System;

using System.Collections.Generic;

using System.Linq;

​

public class Program

{

    // Foo() is now generic and expects an IEnumerable, instead of an array

    static void Foo<T>(IEnumerable<T> arr) 

    {

        Console.WriteLine(arr.First());

        var next = arr.Skip(1);

        if (next.Any()) Foo(next);

    }

​

    // but Main() is unchanged: still using an int array

    static void Main(string[] args) 

    {

        int[] myArray = {4,6,78,9,0};

        Foo(myArray);

    }

}