#include <stdio.h>
#include <bits/stdc++.h>
#include <atcoder/all>
using namespace atcoder;
using mint = modint998244353;
using namespace std;
#define rep(i,n) for (int i = 0; i < (n); ++i)
#define Inf32 1000000001
#define Inf64 1000000000000000001

long long op(long long a,long long b){
	return max(a,b);
}
long long e(){
	return -Inf64;
}
int main(){
	long long N,K;
	cin>>N>>K;
	vector<long long> t(N),x(N),c(N);
	rep(i,N)cin>>t[i];
	rep(i,N)cin>>x[i];
	rep(i,N)cin>>c[i];
	vector<vector<long long>> y;
	vector<long long> ys;
	rep(i,N){
		y.push_back({t[i]*K+x[i],t[i]*K-x[i],c[i]});
		ys.push_back(t[i]*K-x[i]);
	}
	ys.push_back(0);
	sort(ys.begin(),ys.end());
	ys.erase(unique(ys.begin(),ys.end()),ys.end());
	segtree<long long,op,e> seg(ys.size());
	{
		int d = distance(ys.begin(),lower_bound(ys.begin(),ys.end(),0));
		seg.set(d,0);
	}
	sort(y.begin(),y.end());
	rep(i,y.size()){
		int d = distance(ys.begin(),lower_bound(ys.begin(),ys.end(),y[i][1]));
		long long v = seg.prod(0,d+1) + y[i][2];
		seg.set(d,max(seg.get(d),v));
	}
	cout<<seg.all_prod()<<endl;
    return 0;
}