$previous = ($start-$show);
unless($previous < 1){ # unless we're already at the beginning
    print qq~<a href="$url?start=$previous&show=$show">
    Previous $show</a>~;
    }
	
$next = ($start+$show);
unless($next > $c){ # unless we're already at the end
    print qq~<a href="$url?start=$next&show=$show">
    Next $show</a>~;
    }