Problem Statement
Find the number of sequences of integers with ~N~ terms, ~A=(a_1,a_2,\ldots,a_N)~ , that satisfy the following conditions, modulo ~998244353~ .
- ~0 \leq a_1 \leq a_2 \leq \ldots \leq a_N \leq M~ .
- For each ~i=1,2,\ldots,N-1~ , the remainder when ~a_i~ is divided by ~3~ is different from the remainder when ~a_{i+1}~ is divided by ~3~ .
Constraints
- ~2 \leq N \leq 10^7~
- ~1 \leq M \leq 10^7~
- All values in the input are integers.
Input
The input is given from Standard Input in the following format:
~N~ ~M~
Output
Print the answer.
Sample Input 1
3 4
Sample Output 1
8
Here are the eight sequences that satisfy the conditions.
- ~(0,1,2)~
- ~(0,1,3)~
- ~(0,2,3)~
- ~(0,2,4)~
- ~(1,2,3)~
- ~(1,2,4)~
- ~(1,3,4)~
- ~(2,3,4)~
Sample Input 2
276 10000000
Sample Output 2
909213205
Be sure to find the count modulo ~998244353~ .
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