from math import gcd
n, k = list(map(int, input().split()))
A = list(map(int, input().split()))
N = 10**6
dp = [[] for _ in range(N+1)]
ep = [0] * (N+1)
for a in range(2, N+1):
    for b in range(a, N+1, a):
        dp[b].append(a)

for a in A:
    for b in dp[a]:
        ep[b] += 1

c = (n-1) // k + 1
ans = 1
for a in range(2, N+1):
    if ep[a] > c:
        ans = ans * a // gcd(ans, a)
print(ans)