n, x = map(int, input().split())
A = list(map(int, input().split()))
B = list(map(int, input().split()))

INF = 10**18

A = [a-x for a in A]
s = sum(A)

if s >= 0:
    print(0)
    exit()

if max(A) < 0:
    print(-1)
    exit()

from collections import defaultdict
dp = defaultdict(lambda: INF)
dp[s] = 0
for a, b in zip(A, B):
    if a >= 0:
        continue
    nx = defaultdict(lambda: INF)
    for k, v in dp.items():
        nx[k] = min(nx[k], v)
        nx[k-a] = min(nx[k-a], v+b)
    dp = nx
ans = INF
for k, v in dp.items():
    if k >= 0:
        ans = min(ans, v)
if ans != INF:
    print(ans)
else:
    print(-1)