题目描述
Problem Description
We sort a permutation in increasing order using the following method:
One operation: Denote the first number as $k$. Find $k-1$ in the permutation (if $k=1$, take $n$ instead), and move $k-1$ to the first position of the permutation, shifting the intermediate numbers one position to the right.
The value of one operation: The original position of $k-1$ (or $n$) in the permutation (numbered starting from 0).
The value of a permutation: The sum of the values of each operation until the permutation is sorted.
Given $n$ and $m$, find the sum of the values of all $n!$ permutations, modulo $m$.
Input Format
One line containing two positive integers, $n$ and $m$.
Output Format
One line containing one integer, the answer modulo $m$.
Sample Input and Output
Input Sample #1
2 100
Output Sample #1
1
Input Sample #2
3 100
Output Sample #2
15
Input Sample #3
10 1000
Output Sample #3
100
Input Sample #4
500 100000
Output Sample #4
60000
Input Sample #5
100000 1000
Output Sample #5
0
Notes
For all data, $2 \leq n \leq 1000000$, $2 \leq m \leq 10^9$.
| Subtask Number | Additional Constraints | Score |
|---|---|---|
| 1 | $n \leq 10$ | 10 |
| 2 | $n \leq 2000$ | 60 |
| 3 | None | 30 |
输入格式
见题面 Input 部分
输出格式
见题面 Output 部分