include[HTML_REMOVED]
using namespace std;
int main()
{
long long n,k;
cin>>n>>k;
long long num[100005];
long long b[100005];
long long sum=0;
memset(num,0,sizeof(num));
memset(b,0,sizeof(b));
for(int i=1;i<=n;i)
cin>>num[i];
long long z=0;
long long all=0;
long long maxx=0;
for(int i=1;i<=n;i)
{
cin>>b[i];
if(b[i]==1)
sum+=num[i];
if(i==k)
{
for(int j=0;j[HTML_REMOVED]k)
{
if(b[i-k]==0)
all-=num[i-k];
if(b[i]==0)
all+=num[i];
maxx=max(maxx,all);
}
else
;
}
cout<<sum+maxx<<endl;
return 0;
}