题目描述
Problem Statement
We define sequences S_n as follows.
- S_1 is a sequence of length 1 containing a single 1.
- S_n (n is an integer greater than or equal to 2) is a sequence obtained by concatenating S_{n-1}, n, S_{n-1} in this order.
For example, S_2 and S_3 is defined as follows.
- S_2 is a concatenation of S_1, 2, and S_1, in this order, so it is 1,2,1.
- S_3 is a concatenation of S_2, 3, and S_2, in this order, so it is 1,2,1,3,1,2,1.
Given N, print the entire sequence S_N.
Input
Input is given from Standard Input in the following format:
N
Output
Print S_N, with spaces in between.
Constraints
- N is an integer.
- $1 \leq N \leq 16$
Sample Input 1
2
Sample Output 1
1 2 1
As described in the Problem Statement, S_2 is 1,2,1.
Sample Input 2
1
Sample Output 2
1
Sample Input 3
4
Sample Output 3
1 2 1 3 1 2 1 4 1 2 1 3 1 2 1
- S_4 is a concatenation of S_3, 4, and S_3, in this order.
输入格式
见题面 Input 部分
输出格式
见题面 Output 部分
样例输入
2
样例输出
1 2 1