#!/usr/bin/python
import csv
import sys
old = {}
new = {}
for row in csv.reader(open(sys.argv[1])):
old[row[0]] = row
writer = csv.writer(open(sys.argv[3], 'w'))
for row in csv.reader(open(sys.argv[2])):
if row[0] not in old:
writer.writerow(row)