import sys

sys.setrecursionlimit(10**7)
def I(): return int(sys.stdin.readline().rstrip())
def MI(): return map(int,sys.stdin.readline().rstrip().split())
def LI(): return list(map(int,sys.stdin.readline().rstrip().split()))
def LI2(): return list(map(int,sys.stdin.readline().rstrip()))
def S(): return sys.stdin.readline().rstrip()
def LS(): return list(sys.stdin.readline().rstrip().split())
def LS2(): return list(sys.stdin.readline().rstrip())


N,X = MI()
A = LI()
B = LI()

C = [A[i]-X for i in range(N)]
f = sum(C[i] for i in range(N) if C[i] >= 0)

if sum(A[i]-X < 0 for i in range(N)) == N:
    print(-1)
    exit()

D = [(-C[i],B[i]) for i in range(N) if C[i] < 0]
M = len(D)

dp = [[0]*(f+1) for _ in range(M+1)]
for i in range(1,M+1):
    c,b = D[i-1]
    for j in range(f+1):
        if j >= c:
            dp[i][j] = max(dp[i-1][j],dp[i-1][j-c]+b)
        else:
            dp[i][j] = dp[i-1][j]

ans = sum(D[i][1] for i in range(M))-max(dp[-1])
print(ans)