- Time limit: 1.00 s
- Memory limit: 512 MB
Input
The only input line has an integer $n$.
Output
First print an integer $k$: the number of elements in $X$. Then, print an example how to construct $X$. You can print any valid solution.
Constraints
- $1 \le n \le 80$
Input:
11
Output:
5
2 4 6 9 10