friend ostream &operator << (ostream &cout, const Polinom &P1)
    {
        for (int i(0); i<=P1.koeficienti.size(); i++)
        {
            if (P1.koeficienti[i]==0) i++;
            if (i==0)
            {
                cout << P1.koeficienti[i] << " + ";
            }
            if (i==P1.koeficienti.size()-1)
            {
                cout << P1.koeficienti[i] << " " << "x^" << i;
            }
            if (i>0 && i<P1.koeficienti.size()-1)
            {
                cout << P1.koeficienti[i] << " " << "x^" << i << " + ";
            }
        }
    }