\problem{Party Games}

\parpic[r]{\includegraphics[width=0.2\linewidth]{partyGames/party.png}}

You've been invited to a party. The host wants to divide the guests
into 2 teams for party games, with exactly the same number of guests
on each team. She wants to be able to tell which guest is on which
team as she greets them when they arrive. She'd like to do so as
easily as possible, without having to take the time to look up each
guest's name on a list.

Being a good computer scientist, you have an idea: give her a single
string, and all she has to do is compare the guest's name
alphabetically to that string. To make this
even easier, you would like the string to be as short as possible.

Given the unique names of $n$ party guests ($n$ is even), find the
shortest possible string S such that exactly half the names are less
than or equal to S, and exactly half are greater than S. If there are
multiple strings of the same shortest possible length, choose the
alphabetically smallest string from among them.

\subsection*{Input}

There may be multiple test cases in the input. 

Each test case will begin with an even integer $n$ ($2\leq n\leq
1,000$) on its own line.

On the next $n$ lines will be names, one per line. Each name will be a
single word consisting only of capital letters and will be no longer
than 30 letters. 

The input will end with a 0 on its own line.

\subsection*{Output}

For each case, print a single line containing the shortest possible
string (with ties broken in favor of the alphabetically smallest) that
your host could use to separate her guests. The strings should be
printed in all capital letters.

\subsection*{Example}

Given the input
\verbfile{partyGames/sample.judge}

the output would be
\verbfile{partyGames/sample.out}
