#include <bits/stdc++.h>
//#include <atcoder/modint>

using namespace std;
//using namespace atcoder;
using ll = long long;
//using mint = modint998244353;

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

    /*
       dp(i, j, k) = 左の家にi個、右の家にj個行って、左(k=0),右(k=1)にいる時の最小値
    */

    ll N, S, sm=0;
    cin >> N >> S;
    vector<ll> X(N), W(N);
    for (int i=0; i<N; i++){
        cin >> X[i];
        X[i] -= S;
    }
    for (int i=0; i<N; i++){
        cin >> W[i];
        sm += W[i];
    }
    
    vector<ll> nx, px(1, 0), nw, pw(1, 0), ns(1, 0), ps(1, 0);
    for (int i=0; i<N; i++){
        if (X[i] < 0){
            nx.push_back(-X[i]);
            nw.push_back(W[i]);
        }
        else{
            px.push_back(X[i]);
            pw.push_back(W[i]);
        }
    }
    nx.push_back(0);
    nw.push_back(0);
    reverse(nx.begin(), nx.end());
    reverse(nw.begin(), nw.end());
    
    ll NP=px.size(), NN=nx.size();
    for (int i=1; i<NN; i++) ns.push_back(ns.back()+nw[i]);
    for (int i=1; i<NP; i++) ps.push_back(ps.back()+pw[i]);

    vector dp(NN, vector(NP, vector<ll>(2, 1e18)));
    dp[0][0][0] = 0;
    dp[0][0][1] = 0;

    auto chmin=[&](ll &x, const ll &y)->void{
        if (x > y) x = y;
    };

    for (int i=0; i<NN; i++){
        for (int j=0; j<NP; j++){
            //(i, j)まで運送した時の重量
            ll wei = sm-ns[i]-ps[j], dis;
            //左->右
            if (j != NP-1){
                dis = nx[i]+px[j+1];
                chmin(dp[i][j+1][1], dp[i][j][0]+dis*wei);
            }
            //右->右
            if (j != NP-1){
                dis = px[j+1]-px[j];
                chmin(dp[i][j+1][1], dp[i][j][1]+dis*wei);
            }
            //右->左
            if (i != NN-1){
                dis = nx[i+1]+px[j];
                chmin(dp[i+1][j][0], dp[i][j][1]+dis*wei);
            }
            //左->左
            if (i != NN-1){
                dis = nx[i+1]-nx[i];
                chmin(dp[i+1][j][0], dp[i][j][0]+dis*wei);
            }
        }
    }

    cout << min(dp[NN-1][NP-1][0], dp[NN-1][NP-1][1]) << endl;

    return 0;
}