#include <fstream>
#define endl '\n'
using namespace std;

ifstream fin("krasi.in");
ofstream fout("krasi.out");

const int MAX=100024;
int n, k, s[MAX], sum[MAX], zeros[MAX];

int main()
{
    fin>>n>>k;
    fin>>s[1];
    sum[1]=s[1];
    if(s[1]==0)
        zeros[1]=1;

    for(int i=2; i<=n; ++i)
    {
        fin>>s[i];
        sum[i]=sum[i-1]+s[i];
        zeros[i]=zeros[i-1];
        if(s[i]==0)
            zeros[i]++;
    }

    int maxs=0;
    for(int i=1; i<=n; ++i)
    {
        for(int j=i; j<=n; ++j)
        {
            int z=zeros[j]-zeros[i-1];
            if(z>k) break;

            int curr=sum[j]-sum[i-1];
            if(curr>maxs)
                maxs=curr;
        }
    }

    fout<<maxs<<endl;

    fin.close();
    fout.close();

    return 0;
}