You've got an $*n* × *n* × *n*$ cube, split into unit cubes. Your task is to number all unit cubes in this cube with positive integers from $1$ to $*n*^{3}$ so that:
- each number was used as a cube's number exactly once;
- for each
$1 ≤ *i* < *n*^{3}$, unit cubes with numbers$*i*$and$*i* + 1$were neighbouring (that is, shared a side); - for each
$1 ≤ *i* < *n*$there were at least two different subcubes with sizes$*i* × *i* × *i*$, made from unit cubes, which are numbered with consecutive numbers. That is, there are such two numbers$*x*$and$*y*$, that the unit cubes of the first subcube are numbered by numbers$*x*$,$*x* + 1$,$...$,$*x* + *i*^{3} - 1$, and the unit cubes of the second subcube are numbered by numbers$*y*$,$*y* + 1$,$...$,$*y* + *i*^{3} - 1$.
Find and print the required numeration of unit cubes of the cube.
Input
The first line contains a single integer $*n*$ ($1 ≤ *n* ≤ 50$) — the size of the cube, whose unit cubes need to be numbered.
Output
Print all layers of the cube as $*n*$ $*n* × *n*$ matrices. Separate them with new lines. Print the layers in the order in which they follow in the cube. See the samples for clarifications.
It is guaranteed that there always is a solution that meets the conditions given in the problem statement.
Note
In the sample the cubes with sizes $2 × 2 × 2$ are numbered with integers $1, ..., 8$ and $5, ..., 12$.
样例
3
1 4 17
2 3 18
27 26 19
8 5 16
7 6 15
24 25 20
9 12 13
10 11 14
23 22 21
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