# 愚直解(小さいケースの検算用)
# bを実際に作って、lcmを計算

import itertools as itr

def gcd(a, b):
    if b == 0:
        return a
    return gcd(b, a % b)

def lcm(a, b):
    return a * b // gcd(a, b)

N, K = map(int, input().split())
a = list(map(int, input().split()))
b = []
for elements in itr.combinations(a, K):
    x = 1
    for y in elements:
        x *= y
    b.append(x)

ans = 1
for bx in b:
    ans = lcm(ans, bx)

print(ans)