|시간 제한||메모리 제한||제출||정답||맞은 사람||정답 비율|
|2 초||512 MB||2||2||2||100.000%|
Snuke’s dictionary contains n distinct words s1, . . . , sn. Each word consists of English lowercase letters. The words are sorted lexicographically, i.e., s1 < · · · < sn. Unfortunately, you can’t read some characters in his dictionary. You replaced those characters with ’?’. Compute the number of ways to replace each ’?’ with an English lowercase letter and make a valid dictionary, modulo 1,000,000,007.
First line of the input contains one integer n (1 ≤ n ≤ 50). Then n lines follow, i’th of then contains word si (1 ≤ |si| ≤ 20, each character in si is an English lowercase letter or a ‘?’).
Print the answer.
2 ?sum??mer c??a??mp
3 snuje ????e snule