|Codeforces Round #191 (Div. 2)|
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.
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.
Print an integer — the maximal number of 1s that can be obtained after exactly one move.
1 0 0 1 0
1 0 0 1
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.