from collections import defaultdict
inf = 10 ** 9


N, X = map(int, input().split())
A = list(map(int, input().split()))
B = list(map(int, input().split()))

if all(a < X for a in A):
    print(-1)
    exit()


score = 0
cost = 0
dp = defaultdict(int)
dp[0] = 0

for a, b in zip(A, B):
    if a >= X:
        score += a - X
        cost += b
    else:
        p = X - a
        ndp = defaultdict(int)
        for k, v in dp.items():
            ndp[k] = max(ndp[k], v)
            ndp[k+p] = max(ndp[k+p], v + b)
        dp = ndp


tmp = cost
for k, v in dp.items():
    if k > score:
        continue
    tmp = max(tmp, cost + v)

print(sum(B) - tmp)