CODEFORCE 327A

cf337a.py

n = int(raw_input())
a = [int(i) for i in raw_input().split(' ')]

def flip(a, i, j):
    for index in range(i, j + 1):
        a[index] = 1 - a[index]

maxCount = -1

for i in range(n):
    for j in range(i, n):
        flip(a, i, j)
        tempMax = sum(a)
        flip(a, i, j)
        maxCount = tempMax if tempMax > maxCount else maxCount

print maxCount