#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const int inf = 1 << 30;
const ll INF = 1LL << 60;
const int dx[] = {1, 0, -1, 0}, dy[] = {0, 1, 0, -1};
#define rep(i, s, t) for (ll i = (ll)s; i < (ll)(t); i++)
#define rrep(i, s, t) for (ll i = (ll)(t) - 1; i >= (ll)(s); i--)
#define all(x) begin(x), end(x)
#define rall(x) rbegin(x), rend(x)

template <class T1, class T2>
bool chmin(T1& x, T2 y) { return x > y ? (x = y, true) : false; }
template <class T1, class T2>
bool chmax(T1& x, T2 y) { return x < y ? (x = y, true) : false; }

template <class T>
using min_heap = priority_queue<T, vector<T>, greater<T>>;
template <class T>
using max_heap = priority_queue<T>;

void solve() {
    ll N, S;
    cin >> N >> S;
    vector<pair<ll, ll>> xw;
    vector<ll> X(N), W(N);
    rep(i, 0, N) cin >> X[i];
    rep(i, 0, N) cin >> W[i];
    rep(i, 0, N) xw.push_back({X[i], W[i]});
    xw.push_back({S, 0});
    sort(all(xw));
    int at = -1;
    N++;
    rep(i, 0, N) {
        if (xw[i].first == S) {
            at = i;
        }
    }
    assert(at != -1);
    vector<ll> sum(N + 1);
    rep(i, 0, N) sum[i + 1] = sum[i] + xw[i].second;
    vector dp(N, vector(N, vector<ll>(2, INF)));
    dp[at][at][0] = 0;
    dp[at][at][1] = 0;
    rep(d, 0, N) {
        rep(l, 0, N) {
            int r = l + d;
            if (r >= N) break;
            if (0 <= l - 1) {
                chmin(dp[l - 1][r][0], dp[l][r][0] + (xw[l].first - xw[l - 1].first) * (sum[N] - sum[r + 1] + sum[l]));
                chmin(dp[l - 1][r][0], dp[l][r][1] + (xw[r].first - xw[l - 1].first) * (sum[N] - sum[r + 1] + sum[l]));
            }
            if (r + 1 < N) {
                chmin(dp[l][r + 1][1], dp[l][r][0] + (xw[r + 1].first - xw[l].first) * (sum[N] - sum[r + 1] + sum[l]));
                chmin(dp[l][r + 1][1], dp[l][r][1] + (xw[r + 1].first - xw[r].first) * (sum[N] - sum[r + 1] + sum[l]));
            }
        }
    }
    ll ans = min(dp[0][N - 1][0], dp[0][N - 1][1]);
    cout << ans << "\n";
}

int main() {
    cin.tie(0)->sync_with_stdio(0);
    cout << fixed << setprecision(15);
    srand(time(NULL));

    int T;
    // cin >> T;
    T = 1;
    while (T--) solve();
}