I found an interesting problem on https://codeforces.com/problemset/problem/327/A:
Iahub got bored, so he invented a game to be played on paper. 

He writes n integers a_1, a_2, ..., a_{n}. Each of those integers can be either 0 or 1. He's allowed to do exactly one move: he chooses two indices i and j (1 ≤ i ≤ j ≤ n) and flips all values a_{k} for which their positions are in range [i, j] (that is i ≤ k ≤ j). Flip the value of x means to apply operation x = 1 - x.

The goal of the game is that after exactly one move to obtain the maximum number of ones. Write a program to solve the little game of Iahub.


-----Input-----

The first line of the input contains an integer n (1 ≤ n ≤ 100). In the second line of the input there are n integers: a_1, a_2, ..., a_{n}. It is guaranteed that each of those n values is either 0 or 1.


-----Output-----

Print an integer — the maximal number of 1s that can be obtained after exactly one move. 


-----Examples-----
Input
5
1 0 0 1 0

Output
4

Input
4
1 0 0 1

Output
4



-----Note-----

In the first case, flip the segment from 2 to 5 (i = 2, j = 5). That flip changes the sequence, it becomes: [1 1 1 0 1]. So, it contains four ones. There is no way to make the whole sequence equal to [1 1 1 1 1].

In the second case, flipping only the second and the third element (i = 2, j = 3) will turn all numbers into 1.

I tried it in Python, but could not do it. Can you solve it?
n = int(input())
I = list(map(int, input().split()))
d = []
for val in I:
    d.append(val)
res = 0;
for i in range (0, n):
    for j in range (i, n):
        cnt = 0;
        for k in range (0, n):
            if k >= i and k <= j:
                cnt = cnt + 1 - d[k];
            else:
                cnt = cnt + d[k];
        if cnt > res:
            res = cnt;
print (res)