There are a bunch of coins on a table, laid out in a straight line.
Each coin has a (positive) value from ~1~ to ~1\,000~. Now, you're going to play a game with a friend.

At every turn, you must remove a coin from one end of the line.
Turns alternate, so your friend goes immediately after you're done.
The game ends when there are no coins remaining.

An example game:
The coins start like this:
~4, 4, 9, 4~
You always go first, so you take the ~4~ from the left side:
~4, 9, 4~
Your friend takes any of the ~4~s (it doesn't matter)
~9, 4~
Now you can take the ~9~, and your friend takes the remaining ~4~.

Your score, in this case, is ~4+9 = 13~.
(In this case, you can always beat your friend.)
Find the maximum possible score you can achieve.

Input Specification

~N \le 1\,000~, the number of coins.
~N~ lines, each with the value of a coin.

Output Specification

Your maximum possible score, provided that you go first and your friend plays perfectly.