#include <iostream>
#include <algorithm>
using namespace std;

int kadane(int array[], int n){
        int min_current = array[0];
        int min_global = array[0];
        for(int i =1; i<n;i++){
            min_current = min(array[i], array[i]+ min_current);
            if(min_current<min_global)
                min_global = min_current;
        }
        return min_global;
    }

int main() {
    int n;
    int arr[100];
    cin>>n;
    for(int i =0;i<n;i++)
        cin>>arr[i];

    int nrofone = 0;
    for(int i =0;i<n;i++)
        if(arr[i] ==1){
            nrofone++;
        }
    for(int i =0;i<n;i++)
        if(arr[i] ==0){
            arr[i]--;
        }

    cout<<nrofone -kadane(arr, n);

}