#include <bits/stdc++.h>
//#include <ext/pb_ds/assoc_container.hpp>
//using namespace __gnu_pbds;
using namespace std;
using ll=long long;
//typedef tree<int,null_type,less_equal<int>,rb_tree_tag, tree_order_statistics_node_update> ordered_set;
#define mem(a,x) memset(a,x,sizeof(a))
#define int long long
#define fast(s) s.reserve(2000); s.max_load_factor(0.5);
#define F first
#define S second
#define pii pair<int,int>
#define iii tuple<int,int,int>
#define all(p) p.begin(), p.end()
template<typename T> bool maximum(T &A, const T &B) {return A<B? A=B, true: false;}
template<typename T> bool minimum(T &A, const T &B) {return A>B? A=B, true: false;}
template<typename T> T gcd(T t) {return t;}
template<typename T, typename... Args> T gcd(T t, Args... args) {return __gcd(t,args...);};
void print(bool condition=1) {cout<<(condition? "YES\n": "NO\n");}
const int mod=1e9+19972207;
const int base=256;
const int INF=1e18;
const int N=2e5+5, M=5e7;
int n, k, c[N], s[N], f[N], opt[N], best[N], res=-INF, len;
vector<int> num, cand, add[N], del[N];
multiset<int> ms;
void file()
{
#define task "codeforces"
if(fopen(task".inp","r"))
{
freopen(task".inp","r",stdin);
freopen(task".out","w",stdout);
}
ios_base::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
}
struct Persistent
{
int sum[M], cnt[M], L[M], R[M];
int idx=0, ver[N];
int new_node()
{
++idx;
sum[idx]=cnt[idx]=0;
L[idx]=R[idx]=0;
return idx;
}
int Build(int l, int r)
{
int p=new_node();
if(l==r) return p;
int mid=(l+r)>>1;
L[p]=Build(l,mid);
R[p]=Build(mid+1,r);
return p;
}
int update(int id, int l, int r, int i)
{
int p=new_node();
if(l==r)
{
sum[p]=sum[id]+num[i-1];
cnt[p]=cnt[id]+1;
return p;
}
int mid=(l+r)>>1;
if(i<=mid)
{
L[p]=update(L[id],l,mid,i);
R[p]=R[id];
}
else
{
L[p]=L[id];
R[p]=update(R[id],mid+1,r,i);
}
sum[p]=sum[L[p]]+sum[R[p]];
cnt[p]=cnt[L[p]]+cnt[R[p]];
return p;
}
int find_kth(int ptl, int ptr, int l, int r, int k)
{
if(l==r) return num[l-1];
int mid=(l+r)>>1;
int _count=cnt[R[ptr]]-cnt[R[ptl]];
if(_count>=k) return find_kth(R[ptl],R[ptr],mid+1,r,k);
return find_kth(L[ptl],L[ptr],l,mid,k-_count);
}
int get(int ptl, int ptr, int l, int r, int k)
{
if(l==r) return k*num[l-1];
int mid=(l+r)>>1;
int _count=cnt[R[ptr]]-cnt[R[ptl]];
if(_count>=k) return get(R[ptl],R[ptr],mid+1,r,k);
return get(L[ptl],L[ptr],l,mid,k-_count)+sum[R[ptr]]-sum[R[ptl]];
}
} pst;
int cost(int l, int r)
{
if(r-l+1<k) return -INF;
return pst.get(pst.ver[l-1],pst.ver[r],1,len,k)-(f[r]-f[l-1]);
}
void dnc(int l, int r, int optl, int optr)
{
if(l>r) return;
int mid=(l+r)>>1;
for(int i=max(mid+k-1,optl); i<=optr; ++i)
if(maximum(best[mid],cost(mid,i)))
opt[mid]=i;
dnc(l,mid-1,optl,opt[mid]);
dnc(mid+1,r,opt[mid],optr);
}
void Solve()
{
cin>>n>>k;
for(int i=1; i<=n; ++i) cin>>c[i];
for(int i=1; i<=n; ++i) cin>>s[i];
for(int i=1; i<=n; ++i) f[i]=f[i-1]+c[i];
for(int i=1; i<=n; ++i) num.push_back(s[i]);
sort(all(num));
num.erase(unique(all(num)),num.end());
len=(int)num.size();
pst.ver[0]=pst.Build(1,len);
for(int i=1; i<=n; ++i)
{
int p=upper_bound(all(num),s[i])-num.begin();
pst.ver[i]=pst.update(pst.ver[i-1],1,len,p);
}
for(int i=1; i<=n; ++i)
{
opt[i]=-1;
best[i]=-INF;
}
dnc(1,n-k+1,1,n);
for(int i=1; i<=n; ++i)
maximum(res,best[i]);
for(int i=1; i<=n; ++i)
if(best[i]==res) cand.push_back(i);
for(int i=0; i<(int)cand.size(); ++i)
{
int l=cand[i];
int x=opt[l], y=(i+1==(int)cand.size()? n: opt[cand[i+1]]);
for(int z=x; z<=y; ++z)
{
if(cost(l,z)==res)
{
int limit=pst.find_kth(pst.ver[l-1],pst.ver[z],1,len,k);
add[l].push_back(limit);
del[z+1].push_back(limit);
}
}
}
cout<<res<<"\n";
}
signed main()
{
file();
Solve();
return 0;
}
