import sys
import string
#import collections

if len(sys.argv) == 1 or sys.argv[1] in {"-h", "--help"}:
 print("usage: uniqueword filename_1 filename_2 ... filename_n")
 sys.exit()
else:
 words = {} 
 # words = collections.defaultdict(int)
 strip = string.whitespace + string.punctuation + string.digits + "\"'"
 for filename in sys.argv[1:]:
 for line in open(filename):
  for word in line.split():
  word = word.strip(strip)
  if len(word) >= 2:
   words[word] = words.get(word, 0) + 1
   # words[word] += 1
 for word in sorted(words):
 print("'{0}' occurs {1} times".format(word,words[word]))