N,X=map(int,input().split())
A=[int(x) for x in input().split()]
B=[int(x) for x in input().split()]
INF=10**18
dp=[INF]*100001
dp[0]=0
for i in range(N):
    ndp=[INF]*100001
    for j in range(-50000,50001):
        if dp[j]==INF:
            continue
        ndp[j+A[i]-X]=min(ndp[j+A[i]-X],dp[j])
        ndp[j]=min(ndp[j],dp[j]+B[i])
    dp=ndp

ans=min(dp[0:50001])
if ans==sum(B):
    print(-1)
else:
    print(ans)