- Time limit: 1.00 s
- Memory limit: 512 MB
A Gray code is a list of all 2^n bit strings of length n, where any two successive strings differ in exactly one bit (i.e., their Hamming distance is one).
Your task is to create a Gray code for a given length n.
Input
The only input line has an integer n.
Output
Print 2^n lines that describe the Gray code. You can print any valid solution.
Constraints
- 1 \le n \le 16
Example
Input:
2
Output:
00 01 11 10