from bisect import bisect_left
import sys
sys.setrecursionlimit(10**6)

INF = 1 << 62
N, S = map(int, input().split())
X = list(map(int, input().split()))
W = list(map(int, input().split()))


memo = {}
def f(p, w, l, r):
    if l == 0 and r == N-1:
        return 0

    if (p, w, l, r) in memo: return memo[p, w, l, r]
    res = INF
    w2 = w - W[p]
    if p == l:
        if l > 0:
            d = X[p] - X[p-1]
            res = min(res, w2 * d + f(l-1, w2, l-1, r))

        if r+1 < N:
            d = X[r+1] - X[p]
            res = min(res, w2 * d + f(r+1, w2, l, r+1))

    if p == r:
        if l > 0:
            d = X[p] - X[l-1]
            res = min(res, w2 * d + f(l-1, w2, l-1, r))

        if r+1 < N:
            d = X[r+1] - X[p]
            res = min(res, w2 * d + f(r+1, w2, l, r+1))

    memo[p, w, l, r] = res
    return res


ans = INF
w = sum(W)
p = bisect_left(X, S)
if p > 0:
    d = S - X[p-1]
    ans = min(ans, w * d + f(p-1, w, p-1, p-1))

d = X[p] - S
ans = min(ans, w * d + f(p, w, p, p))
print(ans)