#include<bits/stdc++.h>
#include<atcoder/segtree>
using namespace std;
long op(long a, long b){return max(a,b);}
long e(){return -1L<<60;}

int main()
{
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int N,K;
    cin>>N>>K;
    vector<long>T(N),X(N),C(N);
    for(long &t:T)cin>>t,t*=K;
    for(long &x:X)cin>>x;
    for(long &c:C)cin>>c;
    vector<long>xs(N),ys(N);
    for(int i=0;i<N;i++)
    {
        xs[i]=T[i]-X[i];
        ys[i]=T[i]+X[i];
    }
    vector<int>ord(N);
    iota(ord.begin(),ord.end(),0);
    sort(ord.begin(),ord.end(),[&](int i, int j)
    {
        return make_pair(xs[i],ys[i])<make_pair(xs[j],ys[j]);
    });
    auto B=ys;
    sort(B.begin(),B.end());
    B.erase(unique(B.begin(),B.end()),B.end());
    for(long &y:ys)y=lower_bound(B.begin(),B.end(),y)-B.begin();
    atcoder::segtree<long,op,e>seg(B.size()+1);
    seg.set(0,0);
    for(int i:ord)
    {
        long x=xs[i],y=ys[i];
        if(x<0)continue;
        seg.set(y,max(0L,seg.prod(0,y+1))+C[i]);
    }
    cout<<seg.all_prod()<<endl;
}