Password Suspects (AC自動機 DP)
You are the computer whiz for the secret organization known as the Sneaky Underground Smug Perpetrators of Evil Crimes and Thefts. The target for SUSPECT's latest evil crime is their greatest foe, the Indescribably Clever Policemen's Club, and everything is prepared. Everything, except for one small thing: the secret password for ICPC's main computer system.
The password is known to consist only of lowercase letters `a'-`z'. Furthermore, through various sneaky observations, you have been able to determine the length of the password, as well as a few (possibly overlapping) substrings of the password, though you do not know exactly where in the password they occur.
For instance, say that you know that the password is 10 characters long, and that you have observed the substrings ``hello" and ``world". Then the password must be either ``helloworld" or ``worldhello".
The question is whether this information is enough to reduce the number of possible passwords to a reasonable amount. To answer this, your task is to write a program that determines the number of possible passwords and, if there are at most 42 of them, prints them all.