import sys
import copy
def ring(H,n):
    if n==0:
        return H[1:]
    elif n==len(H):
        return H[:-2]
    else:
        for i in range(n):
            H.append(H[i])
        for i in range(n+1):
            del(H[0])
        return H

def solve(G,i):
    #n=0或-1，取了之后删除节点
    get_=G[i]
    del(G[i])
    return G,get_

def input_():
    #N=int(input())
    N=int(sys.stdin.readline())
    H=[]
    for i in range(N):
        H.append(int(sys.stdin.readline()))
    return H,N

H,N=input_()
#每个情况都试一遍
max_val=0
for i in range(N):
    ming=H[i]
    hong=0
    G=copy.deepcopy(H)
    ring_=ring(G,i)
    ind=0
    for j in range(N-1):
        #红拿环里第一个
        if j%2==0:
            if int(ring_[0])>int(ring_[-1]):
                ring_,val=solve(ring_,0)
                hong=hong+int(val)
            else:
                ring_,val=solve(ring_,-1)
                hong = hong + int(val)
        else:
            if int(ring_[0])>int(ring_[-1]):
                ring_,val=solve(ring_,0)
                ming=ming+int(val)
            else:
                ring_,val=solve(ring_,-1)
                ming = ming + int(val)
    if abs(ming-hong)>max_val:
        max_val=abs(ming-hong)
print(max_val)