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lol.py

import time


def give_primes_upto(n):
    primes = []
    if n <= 1:
        return primes
    sieve = [True] * (n+1)
    sieve[2] = sieve[3] = False
    for i in range(4, n, 2):
        sieve[i] = False
    for i in range(6, n, 3):
        sieve[i] = False
    for i in range(5, n, 2):
        if sieve[i]:
            for x in range(i**2, n, i):
                sieve[x] = False
    return [idx for idx, x in enumerate(sieve) if x]


if __name__ == '__main__':
    s = time.time()
    print(give_primes_upto(1000))
    print(time.time() - s)