A191

#include <stdio.h>
#include <stdlib.h>
int main()
{
    int n, *a, i, *f, sum = 0, max;
    scanf("%d",&n);

    a = (int *) malloc(n*sizeof(int));
    f = (int *) malloc(n*sizeof(int));
    f[0] = 0;
    for (i=1; i<=n; i++)
    {
        scanf("%d",&a[i]);
        if (a[i] == 1)
        {
            sum++;
            f[i] = f[i-1]-1;
            if (f[i]<0) f[i] = 0;
        }
        else f[i] = f[i-1]+1;
    }
    max = f[1];
    for (i=1; i<=n; i++)
    {
        //printf("%d   ",f[i]);
        if (max < f[i]) max = f[i];
    }
    sum += max;
    printf("%d",sum);
    return 0;
}