Competitions

# Two dimensional arrays

# Print the chessboard

You are given a chessboard of size **n** * **n**. It is filled with numbers from **1** to `n`

in the following way: the first ^{2}**ceil**(`n`

/ ^{2}**2**) numbers from **1** to **ceil**(`n`

/ ^{2}**2**) are written in the cells with even sum of coordinates from left to right from top to bottom. The rest `n`

- ^{2}**ceil**(`n`

/ ^{2}**2**) numbers from **ceil**(`n`

/ ^{2}**2**) + 1 to `n`

are written in the cells with odd sum of coordinates from left to right from top to bottom. The operation ^{2}**ceil**(**x** / **y**) means division **x** by **y** rounded up.

#### Input

One integer **n** (**1** ≤ **n** ≤ **9**).

#### Output

Print the matrix - chessboard in the given manner. Watch for allignment!

Input example #1

5

Output example #1

1 14 2 15 3 16 4 17 5 18 6 19 7 20 8 21 9 22 10 23 11 24 12 25 13

Input example #2

6

Output example #2

1 19 2 20 3 21 22 4 23 5 24 6 7 25 8 26 9 27 28 10 29 11 30 12 13 31 14 32 15 33 34 16 35 17 36 18