Keyence Repetition

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Points: 0.70
Time limit: 6.0s
Memory limit: 1G

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Problem type
Problem Statement

Let ~s~ be the concatenation of ~N~ copies of keyence . Consider deleting zero or more characters from ~s~ and concatenating the remaining characters without changing the order to make a new string ~s^{\prime}~ .

There are ~2^{7N}~ ways to choose the positions at which we delete the characters. Among them, how many make ~s^{\prime}~ equal to ~t~ ? Find the count modulo ~998244353~ .

Constraints
  • ~1 \leq N \leq 10^{18}~
  • ~1 \leq |t| \leq 2.5 \times 10^5~
  • ~t~ is a string consisting of c , e , k , n , and y .

Input

Input is given from Standard Input in the following format:

~N~

~t~

Output

Print the number of ways to choose the positions at which we delete the characters so that ~s^{\prime}~ will be equal to ~t~ , modulo ~998244353~ .


Sample Input 1
2
key
Sample Output 1
6
  • We have ~s=~ keyencekeyence .
  • There are six ways to choose the positions at which we delete the characters so that ~s^{\prime}=~ key .

Sample Input 2
2
ccc
Sample Output 2
0
  • There are zero ways to choose the positions at which we delete the characters so that ~s^{\prime}=~ ccc .

Sample Input 3
100
keyneeneeeckyycccckkke
Sample Output 3
275429980
  • Be sure to find the count modulo ~998244353~ .

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