#include <bits/stdc++.h>
using namespace std;
# pragma GCC target("avx2")
# pragma GCC optimize("O3")
# pragma GCC optimize("unroll-loops")
#define rep(i, n) for(int i=0;i<(n);i++)
using ll = long long;
const ll INF = 1LL << 60;
void chmin(ll &a, ll b) { if(a > b) a = b; }

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);

    ll n, s; cin >> n >> s;
    vector<ll> x(n), w(n);
    rep(i, n) cin >> x[i];
    rep(i, n) cin >> w[i];
    vector dp(2, vector(n + 1, vector(2, INF)));

    vector<ll> sum(n + 1, 0);
    rep(i, n) sum[i + 1] = sum[i] + w[i];
    for(int l = n - 1; l >= 0; l --) {
        rep(j, n + 1) rep(k, 2) dp[1][j][k] = INF;
        rep(k, 2) chmin(dp[0][l + 1][k], abs(x[l] - s) * sum[n]);

        for(int r = l + 1; r <= n; r ++) {
            ll val = sum[n] - sum[r] + sum[l];
            if(r < n) {
                chmin(dp[0][r + 1][1], dp[0][r][0] + val * abs(x[l] - x[r]));
                chmin(dp[0][r + 1][1], dp[0][r][1] + val * abs(x[r - 1] - x[r]));
            }
            if(l > 0) {
                chmin(dp[1][r][0], dp[0][r][0] + val * abs(x[l] - x[l - 1]));
                chmin(dp[1][r][0], dp[0][r][1] + val * abs(x[r - 1] - x[l - 1]));
            }
        }
        if(l) swap(dp[0], dp[1]); 
    }
    cout << min(dp[0][n][0], dp[0][n][1]) << endl;

    return 0;
}