Hello you all! im developping an application that will find the sum of all even terms of the fibonacci sequence. The last term of this sequence is 4,000,000 . There is something wrong in my code but I cannot find the problem since it makes sense to me. Can you please help me?

using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            long[] arr = new long [1000000] ;
            long i= 2;
            arr[i-2]=1;
            arr[i-1]=2;
            long n= arr[i];

           long s=0;
            for (i=2 ; n <= 4000000; i++)
            {

                arr[i] = arr[(i - 1)] + arr[(i - 2)];
            }
            for (long f = 0; f <= arr.Length - 1; f++)
            {
                if (arr[f] % 2 == 0)
                    s += arr[f];
            }
            Console.Write(s);
            Console.Read();

        }
    }
}