def get_pages_within(pages):
    for page_num in range(1,pages+1):
        wb_data = requests.get('http://bj.58.com/shoujihao/pn{}/'.format(page_num))
        soup = BeautifulSoup(wb_data.text,'lxml')
        numbers = soup.select('strong.number')
        prices = soup.select('b.price')
        links = soup.select('a.t')

        for number, price, link in zip(numbers,prices,links):
            data = {
                'title':number.get_text(),
                'price':price.get_text(),
                'link' :link.get('href')
            }
            shoujihao.insert_one(data)
        print('Done')