#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  int a[n];
  int max = 0, current = 0, re = 0;
  for (int i = 0; i < n; i++) {
    cin >> a[i];
    if (a[i] == 0) {
      current++;
    } else {
      re++;
      current--;
    }
    if (current < 0) {
      current = 0;
    }
    if (current > max) {
      max = current;
    }
  }
  if (re == n) {
    re--;
  }
  cout << re + max;
  return 0;
}
