#include <bits/stdc++.h>

#define snd(t) std::get<1>(t)

using ll = std::int64_t;
using TR = std::tuple<ll, ll, ll>;

struct SegmentTree{
    int numLeave;
    std::vector<ll> data;

    SegmentTree(int n){
        int m = 1;
        while(m < n){m *= 2;}
        numLeave = m;
        data = std::vector<ll>(m * 2, std::numeric_limits<ll>::min());
    }

    void set(int k, ll v){
        k += numLeave;
        data[k] = v;
        while(k >= 2){
            k /= 2;
            data[k] = std::max(data[2 * k], data[2 * k + 1]);
        }
    }

    ll max(int l, int r){
        l += numLeave;
        r += numLeave;
        ll res = std::numeric_limits<ll>::min();
        while(l < r){
            if(l & 1){res = std::max(res, data[l]); l += 1;}
            if(r & 1){r -= 1; res = std::max(res, data[r]);}
            l /= 2; r /= 2;
        }
        return res;
    }

    ll get(int k){
        return data[k + numLeave];
    }
};

int main(){
    std::cin.tie(nullptr);
    std::ios::sync_with_stdio(false);

    int N;
    ll K;
    std::cin >> N >> K;

    std::vector<ll> T(N), X(N), C(N);
    for(int i=0;i<N;i++){
        std::cin >> T[i];
    }
    for(int i=0;i<N;i++){
        std::cin >> X[i];
    }
    for(int i=0;i<N;i++){
        std::cin >> C[i];
    }

    std::vector<TR> points;
    std::vector<ll> beta{0};
    for(int i=0;i<N;i++){
        ll a = X[i] + K * T[i], b = -X[i] + K * T[i];
        points.emplace_back(a, b, C[i]);
        beta.emplace_back(b);
    }
    std::sort(std::begin(points), std::end(points));
    std::sort(std::begin(beta), std::end(beta));
    beta.erase(std::unique(std::begin(beta), std::end(beta)), std::end(beta));

    for(int i=0;i<N;i++){
        snd(points[i]) = std::lower_bound(std::begin(beta), std::end(beta), snd(points[i])) - std::begin(beta);
    }

    SegmentTree seg(beta.size());
    seg.set(std::lower_bound(std::begin(beta), std::end(beta), 0) - std::begin(beta), 0);
    for(int i=0;i<N;i++){
        auto [_, b, c] = points[i];
        ll v = seg.max(0, b + 1);
        if(v != std::numeric_limits<ll>::min()){v += c;}
        seg.set(b, v);
    }

    ll res = seg.max(0, beta.size());
    std::cout << res << std::endl;
}