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,a in enumerate(A):
    ndp=[INF]*100001
    for j in range(-50000,50001):
        ndp[j+a-X]=min(ndp[j+a-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)