题目描述
Problem Statement
Below, a permutation of $(1,2,\ldots,N)$ is simply called a permutation.
For two permutations $A=(A_1,A_2,\ldots,A_N),B=(B_1,B_2,\ldots,B_N)$, let us define their similarity as the number of integers i between 1 and N-1 such that:
- (A_{i+1}-A_i)(B_{i+1}-B_i)>0.
Find the number, modulo a prime number P, of pairs of permutations (A,B) whose similarity is K.
Input
The input is given from Standard Input in the following format:
N K P
Output
Print the answer.
Constraints
- $2\leq N \leq 100$
- $0\leq K \leq N-1$
- $10^8 \leq P \leq 10^9$
- P is a prime number.
- All values in the input are integers.
Sample Input 1
3 1 282282277
Sample Output 1
16
For instance, below is a pair of permutations that satisfies the condition.
- A=(1,2,3)
- B=(1,3,2)
Here, we have (A_2 - A_1)(B_2 -B_1) > 0 and (A_3 - A_2)(B_3 -B_2) < 0, so the similarity of A and B is 1.
Sample Input 2
50 25 998244353
Sample Output 2
131276976
Print the number modulo P.
输入格式
见题面 Input 部分
输出格式
见题面 Output 部分