atcoder#ARC140F. [ARC140F] ABS Permutation (Count ver.)

[ARC140F] ABS Permutation (Count ver.)

Score : 900900 points

Problem Statement

Find the number of permutations P=(P1,P2,,PN)P=(P_1,P_2,\dots,P_N) of (1,2,,N)(1,2,\dots,N) that satisfy the following, modulo 998244353998244353, for each K=0,1,2,,N1K=0,1,2,\dots,N-1.

  • There are exactly KK integers ii such that 1iN11 \le i \le N-1 and PiPi+1=M|P_i - P_{i+1}|=M.

Constraints

  • 2N2500002 \le N \le 250000
  • 1MN11 \le M \le N-1
  • All values in input are integers.

Input

Input is given from Standard Input in the following format:

NN MM

Output

Print the number of permutations that satisfy the condition, modulo 998244353998244353, for each K=0,1,2,,N1K=0,1,2,\dots,N-1.

3 1
0 4 2
  • For K=0K=0, the condition is satisfied by no permutations PP.
  • For K=1K=1, the condition is satisfied by four permutations PP: (1,3,2),(2,1,3),(2,3,1),(3,1,2)(1,3,2),(2,1,3),(2,3,1),(3,1,2).
  • For K=2K=2, the condition is satisfied by two permutations PP: (1,2,3),(3,2,1)(1,2,3),(3,2,1).
4 3
12 12 0 0
10 5
1263360 1401600 710400 211200 38400 3840 0 0 0 0