Taro and Jiro will play the following game against each other.

Initially, they are given a sequence a = (a_1, a_2, \ldots, a_N). Until a becomes empty, the two players perform the following operation alternately, starting from Taro:

* Remove the element at the beginning or the end of a. The player earns x points, where x is the removed element.



Let X and Y be Taro's and Jiro's total score at the end of the game, respectively. Taro tries to maximize X - Y, while Jiro tries to minimize X - Y.

Assuming that the two players play optimally, find the resulting value of X - Y.

Constraints

* All values in input are integers.
* 1 \leq N \leq 3000
* 1 \leq a_i \leq 10^9

Input

Input is given from Standard Input in the following format:


N
a_1 a_2 \ldots a_N


Output

Print the resulting value of X - Y, assuming that the two players play optimally.

Examples

Input

4
10 80 90 30


Output

10


Input

3
10 100 10


Output

-80


Input

1
10


Output

10


Input

10
1000000000 1 1000000000 1 1000000000 1 1000000000 1 1000000000 1


Output

4999999995


Input

6
4 2 9 7 1 5


Output

2
N=int(input())
a=[int(i) for i in input().split()]
dp=[[0]*(N+1) for i in range(N+1)]
for d in range(1,N+1):
  for i in range(N+1-d):
    if (N-d)%2==0:
      dp[i][i+d]=max(dp[i+1][i+d]+a[i],dp[i][i+d-1]+a[i+d-1])
    if (N-d)%2==1:
      dp[i][i+d]=min(dp[i+1][i+d],dp[i][i+d-1])
print(2*dp[0][N]-sum(a))
    