Your task is to find the intersection of two sets of positive integers.
Input
The input consists of two sets of positive integers A={a1, a2, ..., an} and B={b1, b2, ..., bk}
represented as two whitespace-separated lists of numbers.
Each list ends with -1, that serves as an end-of-set marker. Repetitions
of elements are possible in the input, but not in the output.
You may assume that 0 < ai, bi < 106 and that the sets A and B are of size
less than 1000.
Output
is list of numbers or word "empty" if intersection is empty.
