import sys
sys.setrecursionlimit(10**6)


try:
    import pypyjit
    pypyjit.set_param('max_unroll_recursion=-1')
except ModuleNotFoundError:
    pass


N = int(input())
A = list(map(int, input().split()))


memo = {}
def f(l, r):
    if l >= r: return 0
    if (l, r) in memo: return memo[l, r]

    res = max(A[l] - A[l+1] + f(l+2, r),
              A[r] - A[r-1] + f(l, r-2))

    memo[l, r] = res
    return res


ans = f(0, 2*N-1)
print(ans)