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.
Input
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 
30 symbols.
Output
Output in an arbitrary order all accounts which, 
in the judges' opinion, are used by the spammer.
Sample
| input | output | 
|---|
| 11
naucoder
iceman
abikbaev
abikbaev
petr
abikbaev
abikbaev
x
abikbaev
acrush
x | x
abikbaev | 
Problem Author: Sergey Pupyrev
Problem Source: XIII-th USU Junior Contest, October 2006