using System;

public class Program

{

    public static void Main()

    {

     long fibo = 0;

     long fiboPrev = 1;

     long sum = 0;

     while(fibo<=4000000)

     {

      if(fibo%2==0)

      sum+=fibo;

      long temp = fibo;

      fibo += fiboPrev;

      fiboPrev = temp;

     }

        Console.WriteLine(sum);

    }

}