Nart27 has post the 10 test cases of this problem.

I got wrong answer of test10, following is the comparison between my result and contents of Nart27's "phone9.out":

________________________________phone9.out
abbacc eeeddfd rrspps uuuvvtt xwwwwx zqooozq wyywxwy tuvvvu sprrrrp ffefed ababbab
222222 3333333 777777 8888888 999999 0000000 9999999 888888 7777777 333333 2222222

________________________________my result
222222 3333333 777777 8888888 999999 0000000 9999999 888888 7777777 333333 2222222
ccacbb eeddfed ppsrpr vvvuuuv ywwyxx zzzoqoo xxxwxxw tvuvvt prppspr deedde baccabc
________________________________


Thers are sentences like this in the problem description:
"If there are more solutions having the minimum number of words, you can choose any single one of them."
can anybody tell me is it really the case?

Sorry it's my fault, there is an other problem in my program. I've got ac!