Recursively drill through files and pull specific ext

#!/usr/bin/python
# coding: utf-8
import sys,os

filetype = sys.argv[1]
startdir = sys.argv[2]
todir = sys.argv[3]

if sys.argv[1] == '-h':
    print ' proper syntax is filetype, starting directory, and to directory i.e. pullfiles.py jpg /tmp /home/user'
    sys.exit()
if len(sys.argv) < 4:
    print ' proper syntax is filetype, starting directory, and to directory i.e. pullfiles.py jpg /tmp /home/user'
    sys.exit()

for root, dir, files in os.walk(str(startdir)):
        for file in files:
            if ("."+filetype) in file:
        os.system('cp ' + root + '/' + file + ' ' + str(todir))