//Susan J. Cheslog
//Discrete Structures Project

#include<iomanip.h>
#include<fstream.h>

const int MAX = 20;
const int EMPTY = 0;

//==============================================================

void main ()

{
	int size; 
	int entry; 
	int row;  
	int col; 
	int lastEntry; 
	int newRow;
	int newCol; 
	int Grid[MAX][MAX];
	ofstream outdata;
	ifstream indata;

	indata.open("sizes.txt");
	outdata.open("results.txt");
		
	indata >> size;

	while(indata)
	{
		outdata << endl << endl;
		
		if (size < 1 || size > MAX || size % 2 == 0)
			outdata << size << " is not a valid size.";
		else 
		{

			for (row = 0; row < size; row ++)
				for (col = 0; col < size; col++)
					Grid[row][col] = EMPTY;

			lastEntry = size * size;
			row = 0;
			col = size/2;
			Grid[row][col] = 1;

			for (entry = 2; entry <= lastEntry; entry++)
			{
				newRow = ((row - 1 + size) % (size));
				newCol = ((col + 1) % (size));

				if (Grid[newRow][newCol] == EMPTY)
				{
					row = newRow;
					col = newCol;
				}
				else
					row = (row + 1) % size;
			Grid[row][col] = entry;
		}

		for (row=0; row < size; row++)
		{
			for (col = 0; col < size; col++)
				outdata << setw(4) << Grid[row][col];
			outdata << endl;
		}
	}
	indata >> size;
}
}