def knapsack_limited(vlst,wlst,mlst,W):
    from collections import deque
    INF = 1<<60
    V = sum(vi*mi for vi,mi in zip(vlst,mlst))
    dp = [INF]*(V+1)
    dp[0] = 0
    Vnow = 0
    for vi,wi,mi in zip(vlst,wlst,mlst):
        Vnow += vi*mi
        for i in range(vi):
            q1 = deque() #idx
            q2 = deque() #val
            for j in range(V+1):
                x = vi*j + i
                if x > Vnow: break
                vx = dp[x] - j*wi
                while q2 and q2[-1] > vx:
                    q1.pop(); q2.pop()
                q1.append(j)
                q2.append(vx)
                dp[x] = q2[0] + j*wi
                if j - q1[0] == mi:
                    q1.popleft(); q2.popleft()
    return dp

n,m = map(int,input().split())
*a, = map(int,input().split())
*k, = map(int,input().split())

num = [0]*(n-1)
for i in range(n-1):
    num[i] = a[i+1]-1
dp = knapsack_limited(a[:n-1],[1]*(n-1),num,0)
#print(dp)
an,kn = a[-1],k[-1]
tot = sum(ai*ki for ai,ki in zip(a,k)) - an*kn
ans = INF = 1<<60
for i,x in enumerate(dp):
    if x==INF: continue
    c = tot-i-m
    if c%an==0 and -c <= an*kn:
        #print(c,i,x,c//an)
        ans = min(ans,x + kn + c//an)
print(ans if ans < INF else -1)