Zbir parnih

#include <iostream>
#include <vector>

using namespace std;

int main()
{
    long double suma(2);
    long i(2);
    vector<long> niz(2);
    niz[0] = 1;
    niz[1] = 2;

    while(1) {
        niz.push_back(niz[i-2] + niz[i-1] );

        if( niz[i] >= 4000000 ) break;

        if ( niz[i] % 2 == 0 ) suma+=niz[i];

        i++;
    }

    cout<<suma<<endl;


    return 0;
}