# Program to generate a list of primes using the Sieve of Eratosthenes
# Sample run:
# Input a positive integer n: 20
# [1, 2, 3, 5, 7, 11, 13, 17, 19]

def init(n):
    '''Return a list of size n; each element "unmarked".'''

def sieve(L):
    '''Modify L to be a list with primes "unmarked" (use Sieve of Eratosthenes).'''

def make_prime_list(L):
    '''Using L, return a list of primes.'''

n = int(input("Input a positive integer n: "))
L = init(n)
sieve(L)
primes_list = make_prime_list(L)
print(primes_list)
