Two identical-looking twins, A and B, have a unique habit: on any given day, one of them only tells the truth and the other only lies, but who is the truth-teller and who is the liar can change from day to day. According to this information, which of the following conversations between them is impossible?

Seven boxes A, C, G, H, J, N, and R are kept one over the other but not necessarily in the same order. Only three boxes are kept above N. Only one box is kept between H and N. Only three boxes are kept between H and A. A is kept at some place above N. R is kept immediately below A. C is kept at one of the places above G. J is not kept immediately above or below H. How many boxes are kept above H?

Seven boxes, G, H, I, J, O, K, and L, are kept one over the other, but not necessarily in the same order. Only I is kept above O. Only G is kept between O and K. Only J is kept below L. How many boxes are kept between H and J?