Code Submission Evaluation System Login

CSES Problem Set

Substrings


Task | Statistics


CSES - Substrings

Time limit:1.00 s Memory limit:512 MB

Your task is to calculate the number of strings of length $n$ whose substring is a given string of length $m$. All strings consist of characters A–Z.

Input

The first input line has an integer $n$: the length of the final string.

The second line has a string of length $m$.

Output

Print the number of strings modulo $10^9+7$.

Constraints
Example

Input:
6
ABCDB


Output:
52

Explanation: The final string will be of the form ABCDB$x$ or $x$ABCDB where $x$ is any character between A–Z.