Score: 600 points
How many strings can be obtained by applying the following operation on a string S exactly K times: "choose one lowercase English letter and insert it somewhere"?
The answer can be enormous, so print it modulo (10^9+7).
Input is given from Standard Input in the following format:
K S
Print the number of strings satisfying the condition, modulo (10^9+7).
5 oof
575111451
For example, we can obtain proofend
, moonwolf
, and onionpuf
, while we cannot obtain oofsix
, oofelevennn
, voxafolt
, or fooooooo
.
37564 whydidyoudesertme
318008117