from common import sieve

primes = sieve(10000).primes()

def count_primes(a, b):
	n = 0
	while True:
		p = n**2 + a*n + b
		if p not in primes:
			break
		n += 1
	return n

max_count = 0
max_pair = (0, 0)

for a in xrange(-999, 1000):
	for b in xrange(-999, 1000):
		c = count_primes(a, b)
		if c > max_count:
			max_count = c
			max_pair = (a, b)

print max_pair[0] * max_pair[1]