import sys
input = sys.stdin.readline

INF = 3 << 59

def solve():
    n, s = map(int, input().split())
    x = list(map(int, input().split()))
    w = list(map(int, input().split()))

    # 累積和
    sumw = [0] * (n + 1)
    for i in range(n):
        sumw[i + 1] = sumw[i] + w[i]

    # dp[cur][r][side]
    dp = [
        [[INF, INF] for _ in range(n + 1)],
        [[INF, INF] for _ in range(n + 1)]
    ]

    for l in range(n - 1, -1, -1):
        # 次の層を初期化
        for j in range(n + 1):
            dp[1][j][0] = dp[1][j][1] = INF

        base = abs(x[l] - s) * sumw[n]
        dp[0][l + 1][0] = min(dp[0][l + 1][0], base)
        dp[0][l + 1][1] = min(dp[0][l + 1][1], base)

        for r in range(l + 1, n + 1):
            val = sumw[n] - sumw[r] + sumw[l]

            # 右を広げる
            if r < n:
                cost0 = dp[0][r][0] + val * abs(x[l] - x[r])
                cost1 = dp[0][r][1] + val * abs(x[r - 1] - x[r])
                dp[0][r + 1][1] = min(dp[0][r + 1][1], cost0, cost1)

            # 左を広げる
            if l > 0:
                cost0 = dp[0][r][0] + val * abs(x[l] - x[l - 1])
                cost1 = dp[0][r][1] + val * abs(x[r - 1] - x[l - 1])
                dp[1][r][0] = min(dp[1][r][0], cost0, cost1)

        if l > 0:
            dp[0], dp[1] = dp[1], dp[0]

    print(min(dp[0][n][0], dp[0][n][1]))


if __name__ == "__main__":
    solve()