а) $a_1 = (1, 0, 0, -1),\quad a_2 = (2, 1, 1, 0),\quad a_3 = (1, 1, 1, 1),\quad a_4 = (1, 2, 3, 4),\quad a_5 = (0, 1, 2, 3);$

б) $a_1 = (1, 1, 1, 1, 0),\quad a_2 = (1, 1, -1, -1, -1),\quad a_3 = (2, 2, 0, 0, -1),\quad a_4 = (1, 1, 5, 5, 2),\quad a_5 = (1, -1, -1, 0, 0).$