public class q2evenfibonacci {
    public static int ans(int n){
        if( n == 0){
            return 1;
        }
        else if(n == 1){
            return  2;
        }
        else{
            return ans(n-1) + ans(n-2);
        }
    }
    public static void main(String args[]){
        int count = 0;
        int answer = 0;
        int sum = 0;
        while(answer < 4000000){
            answer = q2evenfibonacci.ans(count);
            if(answer %2 == 0){
                sum += answer;
            }
            count++;
        }
        System.out.println(sum);
    }
}