a11s.py

def abbrevify(word):
    assert(len(word) >= 4)
    num = len(word) - 2
    return word[0] + str(num) + word[-1]

results = {}

for word in open('/usr/share/dict/words'):
    word = word.strip()
    if len(word) >= 4 and word.islower():
        abbrevd = abbrevify(word)
        given = results.get(abbrevd, [])
        results[abbrevd] = given + [word]


filtered = dict((key,value[0]) for key, value in results.iteritems() if len(value) == 1)

print len(filtered), "words can be unambiguously abbreviated"

for key, value in filtered.iteritems():
   print value, "==>", key