import sys

def get_primes(ceiling):
    numbers_list = set(range(ceiling, 1, -1))
    primes = []
    while numbers_list:
        prime = numbers_list.pop()
        primes.append(prime)
        numbers_list.difference_update(set(range(prime * 2, ceiling + 1, prime)))
    return primes

def get_lcm(range_start, range_end):
    primes_list = get_primes(range_end)
    factors = []
    for i in [j for j in primes_list if j <= range_end]:
        power = 1
        while (i ** power) <= range_end:
            factors.append(i)
            power += 1
    for i in factors:
        range_start *= i
    return range_start

print(get_lcm(1,20))