def primz(max_n):
    primes = range(2,max_n+1)
    index = 0
    while index < len(primes):
        curnum = primes[index]
        primes = sorted(set(primes) - set(range(curnum*2,max_n+1,curnum)))
        index += 1
    return sorted(primes)
print primz(1000)
print len(primz(1000))