#include <iostream>
using namespace std;

int fibonacci(int k)
{
    if (k == 1 || k == 2)
        return k;

    return (fibonacci(k-1) + fibonacci(k-2));
}

int evenfibonacci()
{
    int result = 0;
    for (int k = 1; fibonacci(k) <= 4e6; ++k) {
        if (fibonacci(k) % 2 == 0) {
            result += fibonacci(k);
        }
    }
    return result;
}

int main()
{
	cout << evenfibonacci();
}