Permutation problem - FlandreOJ: Flandre Online Judge
Permutation problem
Time limit: 1000 ms
Memory limit: 256 MB
You are given an integer $k$. Count the number of permutation $P$ of length $n$ that for every $1 \le i \le k$, $P_i \neq i$.
### Input
- A single line contains 2 integers $n, k$.
### Output
- Print the answer, modulo $10^9+7$.
### Constraints
- $1 \le k \le n \le 10^5$.
### Example
Input:
```
3 2
```
Output:
```
3
```
