for (int i = 0; i <= k-1; i++)
        mas3[i] = (mas2[i+1] - mas2[i]) / ((b - a) / n);

    int iterEndl = 0;
    for (int i = 0; i <= k; i++){
            cout << " " << mas[0][i] << ": " << mas3[i] << "\t";
            iterEndl++;
        if (iterEndl == 2){
            cout << endl;
            iterEndl = 0;
        }
    }
    return 0;
}