题目描述
Problem Statement
You are given an integer sequence $A = (A_1, \dots, A_N)$ of length N.
Find the number, modulo 998244353, of permutations $P = (P_1, \dots, P_N)$ of $(1, 2, \dots, N)$ such that:
- there exist exactly K integers i between 1 and (N-1) (inclusive) such that $A_{P_i} \lt A_{P_{i + 1}}$.
Input
Input is given from Standard Input in the following format:
N K
$A_1 \ldots A_N$
Output
Print the answer.
Constraints
- $2 \leq N \leq 5000$
- $0 \leq K \leq N - 1$
- $1 \leq A_i \leq N$ $, (1 \leq i \leq N)$
- All values in input are integers.
Sample Input 1
4 2
1 1 2 2
Sample Output 1
4
Four permutations satisfy the condition: P = (1, 3, 2, 4), (1, 4, 2, 3), (2, 3, 1, 4), (2, 4, 1, 3).
Sample Input 2
10 3
3 1 4 1 5 9 2 6 5 3
Sample Output 2
697112
输入格式
见题面 Input 部分
输出格式
见题面 Output 部分
样例输入
4 2
1 1 2 2
样例输出
4