#!/usr/bin/perl -w
use strict;
my $n= (@ARGV,5)[0];
my @s= (((0)x$n,-1)x$n,(-1)x$n,-1);
my @d= (1,$n+1,-1,-$n-1);
my($p,$d,$v)=(-1,0,0);
while( ! $s[$p+=$d[$d]] ) {
    $s[$p]= ++$v;
    $d= ($d+1)%@d if $s[$p+$d[$d]];
}
printf $_<0?$/:" %".length($v)."d", $_ for @s[0..$v+$n-1];