import sys
input = sys.stdin.readline

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


for i in range(N):
    A[i]-=X

DP=[1<<60]*(2*10**4)
DP[10**4]=0

for i in range(N):
    a=A[i]
    b=B[i]

    NDP=[1<<60]*(2*10**4)

    for j in range(2*10**4):
        if DP[j]>=(1<<60):
            continue
        NDP[j]=min(NDP[j],DP[j]+b)
        NDP[j+a]=min(NDP[j+a],DP[j])
    DP=NDP

ANS=1<<60
for i in range(10**4,2*10**4):
    ANS=min(ANS,DP[i])

if ANS==1<<60 or ANS==sum(B):
    print(-1)
else:
    print(ANS)