Seven boxes B, U, I, L, D, E and R are kept one over the other but not necessarily in the same order. Only three boxes are kept below B. Only one box is kept between L and B. Only three boxes are kept between L and U. U is kept at some place above B. R is kept immediately below U. E is kept at one of the places above I. D is not kept immediately above or below L. Which box is kept at the lowermost position?