Count the number of ways to place $n$ queens on a board of size $n \times n$ so that no two queens are attacking each other.
An example way of placing $5$ queens:
```
X....
...X.
.X...
....X
..X..
```
### Input
- A single integer $n$.
### Output
- The number of ways to place $n$ queens.
### Constraints
- $1 \le n \le 10$.
### Example
Input:
```
5
```
Output:
```
10
```
