#include <stdio.h>

int main(void)
{
	int x=0,y=0, i=0;
	int **snail_array;
	int snail=0, snail_number=0;

	/* input */
	printf("input snail_number : ");
	scanf("%d", &snail_number);

	/* create array */
	snail_array=(int **)malloc(sizeof(int *) * snail_number);
	for(i=0; i<snail_number; i++)
		snail_array[i]=(int *)malloc(sizeof(int) * snail_number);

	/* make snail_arrar */
	for(i=0; i<(snail_number+1)/2; i++)
	{
		for(x=i,y=i; y<snail_number-1-i; y++)
			snail_array[x][y]=snail++;

		for(x=i,y=snail_number-1-i; x<snail_number-1-i; x++)
			snail_array[x][y]=snail++;

		for(x=snail_number-1-i, y=snail_number-1-i; y>i; y--)
			snail_array[x][y]=snail++;

		for(x=snail_number-1-i, y=i; x>i; x--)
			snail_array[x][y]=snail++;
	}

	if(snail_number%2!=0)
		snail_array[(snail_number-1)/2][(snail_number-1)/2]=snail++;

	/* output */
	for(x=0; x<snail_number; x++)
	{
		for(y=0; y<snail_number; y++)
			printf("%d\t", snail_array[x][y]);
		printf("\n");
	}

	/* free */
	for(i=0; i<snail_number; i++)
		free(snail_array[i]);
	free(snail_array);

	return 0;
}