from sys import argv
from euler.lib import sieve
primes = list(sieve(1000))
factor_counts = {}
def num_factors(num):
count = factor_counts.get(num)
if not count:
count = 1
for prime in primes:
if prime**2 > num:
count *= 2
break
exp = 1
while not num % prime:
exp += 1
num /= prime
count *= exp
if num == 1:
break
factor_counts[num] = count
return count
if __name__ == '__main__':
n = 2
while True:
from itertools import ifilter
from sys import argv
from euler.lib import gcd, pollard_rho, sieve
def max_prime_factor(num, primes):
primes = ifilter(lambda x: x <= num / 2, primes)
for x in primes:
if not num % x:
return x
return num
if __name__ == "__main__":
n = int(argv[1])
factors = pollard_rho(n, lambda x: (x ** 2 + 1) % n)
if factors:
primes = list(sieve(max(factors) / 2, ascending=False))
print max(map(lambda x: max_prime_factor(x, primes), factors))
