import sys
input = sys.stdin.readline
from collections import *

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

if max(A)<X:
    print(-1)
    exit()
    
dp = defaultdict(int)
dp[0] = 0

for Ai, Bi in zip(A, B):
    ndp = defaultdict(lambda: 10**18)
    
    for k in dp:
        ndp[k] = min(ndp[k], dp[k]+Bi)
        ndp[k+Ai-X] = min(ndp[k+Ai-X], dp[k])
    
    dp = ndp

ans = 10**18

for k in dp:
    if k>=0:
        ans = min(ans, dp[k])

print(ans)