from math import gcd

class Eratosthenes:
    def __init__(self, n):
        self.isPrime = [True]*(n+1)
        self.minfactor = [-1]*(n+1)
        self.isPrime[0], self.isPrime[1] = False, False
        self.minfactor[1] = 1
        for i in range(2, n+1):
            if self.isPrime[i]:
                self.minfactor[i] = i
                for j in range(i*i, n+1, i):
                    self.isPrime[j] = False
                    if self.minfactor[j] == -1:
                        self.minfactor[j] = i
    
    def factorize(self, n):
        factor = []
        while n > 1:
            p = self.minfactor[n]
            cnt = 0
            while self.minfactor[n] == p:
                n //= p
                cnt += 1
            factor.append((p, cnt))
        return factor
    
    def divisor(self, n):
        ans = [1]
        pf = self.factorize(n)
        for p, c in pf:
            L = len(ans)
            for i in range(L):
                v = 1
                for _ in range(c):
                    v *= p
                    ans.append(ans[i]*v)
        return sorted(ans)

INF = 1<<60

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

def func(limit):
    ans = 0
    for i in range(N):
        left = -1
        right = len(C[i])
        while left+1 < right:
            mid = (left+right)//2
            if C[i][mid][0] < limit:
                left = mid
            else:
                right = mid
        ans += C[i][right][1]
    return ans

E = Eratosthenes(10**5)
C = []
for i in range(N):
    GCD = gcd(A[i], B[i])
    div = E.divisor(A[i])
    stack = [(GCD, 0)]
    for d in div:
        if d <= GCD:
            continue
        cnt = (d-B[i])%d
        while stack and cnt <= stack[-1][1]:
            stack.pop()
        stack.append((d, cnt))
    C.append(stack)
for i in range(N):
    C[i].sort(key=lambda x:x[0])

left = 1
right = min(A)+1
while left+1 < right:
    mid = (left+right)//2
    if func(mid) <= K:
        left = mid
    else:
        right = mid

print(left)