CTF 字符统计1

题目地址：http://sec.hdu.edu.cn/question/web/1047/

题目如下：

给你2秒钟的时间，告诉我下面这坨字符中有多少个s，多少个e，多少个c，多少个l，多少个a和多少个b， 把这些数字串成一个字符串提交一下。只能用脚本来完成了。

看一下题目的源代码：

写出对应的python脚本：

 # coding=UTF-8
import urllib,urllib2,requests
from bs4 import BeautifulSoup
url = "http://sec.hdu.edu.cn/question/web/1047/"
head_info={
'User-Agent':'Mozilla/5.0 (Windows NT 10.0; WOW64; rv:47.0) Gecko/20100101 Firefox/47.0',
'Accept':'text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8',
'Accept-Language':'zh-CN,zh;q=0.8,en-US;q=0.5,en;q=0.3',
'Accept-Encoding':'gzip, deflate',
'Cookie':'JSESSIONID=FA2540037BC70E131CC2837234D92EAD',
'Connection':'keep-alive',
'Cache-Control':'max-age=0',
}

r=requests.get(url,headers=head_info).content
soup=BeautifulSoup(r,'lxml')
str=soup.findAll("pre")
a=str[0].contents
Unicode2str=a[0].encode("utf-8")
ln=len(Unicode2str)

s=0
e=0
c=0
l=0
a=0
b=0
for i in range(ln):
    if (Unicode2str[i] == 's' ):
        s=s+1
    elif (Unicode2str[i]== 'e' ):
        e=e+1
    elif (Unicode2str[i] == 'c' ):
        c=c+1
    elif (Unicode2str[i]== 'l' ):
        l=l+1
    elif (Unicode2str[i] == 'a' ):
        a=a+1
    elif (Unicode2str[i]=='b'):
        b=b+1
    else:
        continue

value='%d' %s +'%d' %e +'%d' %c +'%d' %l +'%d' %a +'%d' %b

getdata={'ans':value}
gdata=urllib.urlencode(getdata)
url2=url+'?'+gdata
print url2
r = requests.get(url2,headers=head_info).content
print r

运行，得到flag。