from bisect import bisect_left

def make_divisors(n):
    lower_divisors, upper_divisors = [], []
    i = 1
    while i**2 <= n:
        if n % i == 0:
            lower_divisors.append(i)
            if i != n // i:
                upper_divisors.append(n // i)
        i += 1
    return lower_divisors + upper_divisors[::-1]

N, K = map(int, input().split())
A = list(map(int, input().split()))
B = list(map(int, input().split()))
divs = [make_divisors(a) for a in A]
cums = [[1 << 60] * len(divs[i]) for i in range(N)]
for i in range(N):
    div = divs[i]
    cum = cums[i]
    for k in range(len(div)):
        d = div[k]
        cum[k] = (B[i] + d - 1) // d * d - B[i]
    for k in range(len(div) - 1, 0, -1):
        cum[k - 1] = min(cum[k], cum[k - 1])

ok = 1
ng = 10**11
while ng - ok > 1:
    mid = (ok + ng) // 2
    cnt = 0
    for i in range(N):
        idx = bisect_left(divs[i], mid)
        if idx == len(divs[i]):
            cnt = K + 1
            break
        cnt += cums[i][idx]
    if cnt <= K:
        ok = mid
    else:
        ng = mid
print(ok)