Consider the following game: Given an initially empty set and a sequence of words, insert each word w in the set if w was not yet in it, and delete w from the set if w was already in it. At the end, print the words that are in the set, and also the words that have been in the set but finally are not in it.
Input
Input is a sequence of words.
Output
Print the words that finally are in the set, one per line and in increasing order. Afterwards, print twenty hyphens in a line, followed by the words that have been in the set but finally are not in it, one per line and in decreasing order.
Input
que qui com on on why quan qui que qui why
Output
com quan qui -------------------- why que on