When 1,5-dibromopentane reacts with ammonia, among several products isolated is a water-soluble compound A that rapidly gives a precipitate of AgBr with acidic AgNO3 solution. Compound A is unchanged when treated with dilute base, but treatment of A with concentrated NaOH and heat gives a new compound B (C10H19N) that decolorizes Br2 in CCl4. Compound B is identical to the product obtained from the reaction sequence shown below. Identify A and B.