**Time limit:**1.00 s**Memory limit:**512 MB

Your task is to calculate the number of strings of length n having a given pattern of length m as their substring. 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 pattern of length m.

# Output

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

# Constraints

- 1 \le n \le 1000
- 1 \le m \le 100

# Example

Input:

6 ABCDB

Output:

52

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