- Time limit: 1.00 s
- Memory limit: 512 MB
Your task is to calculate the number of valid bracket sequences of length n. For example, when n=6, there are 5 sequences:
()()()
()(())
(())()
((()))
(()())
Input
The only input line has an integer n.
Output
Print the number of sequences modulo 10^9+7.
Constraints
- 1 \le n \le 10^6
Example
Input:
6
Output:
5