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

namespace Euler2
{
    //Find the sum of all the even-valued terms in the Fibonacci sequence 
    //which do not exceed four million.
    class Program
    {
        static void Main(string[] args)
        {
            long sum = 2;

            long i = 1;
            long j = 2;

            while(j < 4000000)
            {
                long buff = j;

                j += i;
                i = buff;

                if (j % 2 == 0) sum += j;
            }
            Console.WriteLine("sum of all the even-valued terms in the fibo sequence which do not exceed four million: " + sum);
        }
    }
}