a = [1, 2, 3] b = [1, 2, 3, 4, 5, 6] c = [1, [2, 3]] d = [1, 2, 3, 4, 5, [6, [7]]] e = [1, 2, 3, 4, 5, 6, 7, 8, [9, [10]]]