e-olymp
Problems

Print the chessboard

Print the chessboard

You are given a chessboard of size n * n. It is filled with numbers from 1 to n2 in the following way: the first ceil(n2 / 2) numbers from 1 to ceil(n2 / 2) are written in the cells with even sum of coordinates from left to right from top to bottom. The rest n2 - ceil(n2 / 2) numbers from ceil(n2 / 2) + 1 to n2 are written in the cells with odd sum of coordinates from left to right from top to bottom. The operation ceil(x / y) means division x by y rounded up.

Input

One integer n (1n9).

Output

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

Time limit 1 second
Memory limit 128 MiB
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