#include <bits/stdc++.h>
#define int long long
using namespace std;
const int oo = LLONG_MAX;
const int nmax = 3e5;
const int vmax = 1e9;
int n, k;
int c[nmax + 5], s[nmax + 5];
int r[nmax + 5], poz[nmax + 5];
int sum[nmax + 5];
struct Node
{
Node *st, *dr;
int val, sum;
Node()
{
st = dr = nullptr;
val = sum = 0;
}
Node(int new_val, int new_sum)
{
st = dr = nullptr;
this -> val = new_val;
this -> sum = new_sum;
}
Node(Node *nod, int new_val, int new_sum)
{
this -> st = nod -> st;
this -> dr = nod -> dr;
this -> val = nod -> val + new_val;
this -> sum = nod -> sum + new_sum;
}
Node(Node *son_st, Node *son_dr)
{
this -> st = son_st;
this -> dr = son_dr;
this -> val = this -> sum = 0;
if(son_st != nullptr)
{
this -> val += son_st -> val;
this -> sum += son_st -> sum;
}
if(son_dr != nullptr)
{
this -> val += son_dr -> val;
this -> sum += son_dr -> sum;
}
}
};
Node *rt[nmax + 5];
Node *update(Node *nod, int poz, int val, int a, int b)
{
if(a == b)
{
if(nod == nullptr)
{
return new Node(val, val * a);
}
return new Node(nod, val, val * a);
}
int mij = (a + b) >> 1;
if(poz <= mij)
{
if(nod == nullptr)
{
return new Node(update(nullptr, poz, val, a, mij), nullptr);
}
return new Node(update(nod -> st, poz, val, a, mij), nod -> dr);
}
if(nod == nullptr)
{
return new Node(nullptr, update(nullptr, poz, val, mij + 1, b));
}
return new Node(nod -> st, update(nod -> dr, poz, val, mij + 1, b));
}
pair<int,int> query(Node *nod_st, Node *nod_dr, int k, int a, int b)
{
if(a == b)
{
return {a * k, a};
}
int mij = (a + b) >> 1;
int cnt_dr = 0;
if(nod_dr -> dr != nullptr)
{
cnt_dr += nod_dr -> dr -> val;
}
if(nod_st != nullptr && nod_st -> dr != nullptr)
{
cnt_dr -= nod_st -> dr -> val;
}
if(cnt_dr >= k)
{
if(nod_st == nullptr)
{
return query(nullptr, nod_dr -> dr, k, mij + 1, b);
}
return query(nod_st -> dr, nod_dr -> dr, k, mij + 1, b);
}
pair<int,int> aux = {0, 0};
if(nod_st == nullptr)
{
aux = query(nullptr, nod_dr -> st, k - cnt_dr, a, mij);
}
else
{
aux = query(nod_st -> st, nod_dr -> st, k - cnt_dr, a, mij);
}
if(nod_dr -> dr != nullptr)
{
aux.first += nod_dr -> dr -> sum;
}
if(nod_st != nullptr && nod_st -> dr != nullptr)
{
aux.first -= nod_st -> dr -> sum;
}
return aux;
}
int get_sum(int st, int dr)
{
return sum[dr] - sum[st - 1];
}
int cost(int st, int dr)
{
int rez = -get_sum(st, dr);
pair<int,int> val = query(rt[st - 1], rt[dr], k, 1, vmax);
rez += val.first;
return rez;
}
void divide(int st, int dr, int min_chosen, int max_chosen)
{
if(st > dr)
{
return;
}
int mij = (st + dr) >> 1;
r[mij] = -oo;
poz[mij] = 0;
for(int j=max(min_chosen, mij + k - 1);j<=max_chosen;j++)
{
if(cost(mij, j) > r[mij])
{
poz[mij] = j;
r[mij] = cost(mij, j);
}
}
divide(st, mij - 1, min_chosen, poz[mij]);
divide(mij + 1, dr, poz[mij], max_chosen);
}
signed main()
{
ios::sync_with_stdio(false);
cin.tie(0);
#ifdef home
freopen("nr.in","r",stdin);
freopen("nr.out","w",stdout);
#endif // home
cin>>n>>k;
for(int i=1;i<=n;i++)
{
cin>>c[i];
sum[i] = sum[i - 1] + c[i];
}
rt[0] = new Node();
for(int i=1;i<=n;i++)
{
cin>>s[i];
rt[i] = update(rt[i - 1], s[i], +1, 1, vmax);
}
divide(1, n - k + 1, k, n);
int rez = -oo;
for(int i=1;i+k-1<=n;i++)
{
rez = max(rez, r[i]);
}
cout<<rez<<'\n';
return 0;
}
