from common import sieve

primes = list(sieve(1000000).primes())
primes.sort()

factors = 4

def check_prime_factors(x):
	distinct = set()
	for p in primes:
		while x % p == 0:
			x /= p
			distinct.add(p)
		if x == 1:
			break
	return len(distinct) == factors

n = 644

while True:
	if check_prime_factors(n) and check_prime_factors(n+1) and check_prime_factors(n+2) and check_prime_factors(n+3):
		print n
		break
	n += 1