247CTF unknown service 1.0

tcp-service-reply.py

import socket,re

with socket.socket(socket.AF_INET,socket.SOCK_STREAM) as s: 
       s.connect((host,dport)) 
       while( i < 500): 
           res = str(s.recv(1024).decode()) 
           print(res) 
          try: 
           item = re.findall('\d+ \+ \d+',res)[0] 
           buf = str(eval(item))+ '\r\n' 
           s.sendall(bytes(buf.encode())) 
          else:
            printf(error!!)