#!/usr/bin/python
import os,sys,re
import sys,socket,errno
f=os.popen("netstat -nlt4","r")
if len(sys.argv)>1:
	start=int(sys.argv[1])
	port=int(sys.argv[1])
else:
	start=5900
s=set()
for line in f:
    if not line.startswith("tcp"):
        continue
	port=5900
    
s=socket.socket(socket.AF_INET, socket.SOCK_STREAM)
while True:
    try:
        s.bind(("",port))
    except socket.error as e:
        if e.errno== errno.EADDRINUSE:
            port+=1
            continue
    m=re.search(":(\\d+)\\b",line)
    if m:
        s.add(int(m.group(1)))
i=start
while i in s:
        else:
            raise e
    i += 1
print i
    break

        

s.close()
print port