N, X = map(int, input().split())

A = list(map(lambda x: X - int(x), input().split()))

B = list(map(int, input().split()))

n = sum(A)

if n <= 0:
    
    print(0)
    
    exit()
    
dp = [0] + [sum(B)] * n


for i in range(N):
    
    if A[i] > 0:
        
        for j in range(-1, -n - 2, -1):
            
            dp[j] = min(dp[j], dp[max(j - A[i], -n-1)] + B[i])
            
            


if dp[-1] == sum(B):
    
    print(-1)