There is a famous spammer among our friends. In the end of every
contest he is submitting his incorrect solutions at the speed of
a machine-gun. In addition, he cheats by means of using several
accounts for debugging. The judges eventually decided to
disqualify the spammer. For that, they first want to discover all
of his debugging accounts. The judges know which teams submitted
their solutions in the last ten minutes of a contest. They regard
as the spammer's debugging accounts all accounts which submitted
solutions at least twice during the last ten minutes of the
contest. Your task is to find these accounts.
The first line contains the number N of submissions
in the last 10 minutes (0 ≤ N ≤ 100).
The next N lines contain the names of teams which
submitted their solutions in this period. The names contain only
digits and lowercase English letters. Each name is not longer than
Output in an arbitrary order all accounts which,
in the judges' opinion, are used by the spammer.
Problem Author: Sergey Pupyrev
Problem Source: XIII-th USU Junior Contest, October 2006