import math

def isprime(n):
    """
    determine if n is prime
    """
    for div in range(2, int(math.sqrt(n)+1)):
        if n%div == 0:
            return False
    return True

# use a generator
def primes(n = 2):
    """
    generate primes as needed starting at n
    """
    while True:
        if isprime(n):
            yield n
        n += 1

def n_primes(n = 1000):
    """
    return a list of n primes
    """
    prime_list = []
    for prime in primes():
        prime_list.append(prime)
        if len(prime_list) == n:
            return prime_list

def nth_prime(n = 1000):
    """
    returns the nth prime
    """
    for i, prime in enumerate(primes()):
        if i == n - 1:
            return prime

if __name__ == '__main__':
    """
    a = n_primes(1000)
    a[-1] == 7919
    nth_prime(1000) == 7919
    """
    a = n_primes(1000)
    print a[-1]
    print nth_prime(1000)