#! /bin/sh
read l
case "$l" in
	*[!\ 0-9]*)	echo "Invalid spec (bad char): $l" 1>&2
			exit 1
			;;
esac
set $l
size=$1
#echo "size = $size" 1>&2
shift
i=0
while [ $# -ge 1 ]; do
	n=$1
	for var in bx by ax ay; do
		eval val=$(($n % $size))
		if [ $val -lt 0 -o $val -ge $size ]; then
			echo "Invalid spec (bad $var value $val in $1): $l" 1>&2
			exit 1
		fi
		eval $var=$val
		n=$(($n / $size))
	done
	case $n in
		0)	;;
		*)	echo "Invalid spec (overflow $n in $1): $l" 1>&2
	esac
	eval ax$i=$ax
	eval ay$i=$ay
	eval bx$i=$bx
	eval by$i=$by
#	echo "$i = ($ax,$ay) - ($bx,$by)" 1>&2
	i=$(($i+1))
	shift
done
(
echo "ppmmake \#7f7f7f $(((50*$size)+2)) $(((50*$size)+2)) |
  pnmdepth 255 |
  pnmmpaste "\\
coords=`count from 0 to $(($size-1))`
for y in $coords; do
	for x in $coords; do
		echo "	greysquare $((($x*50)+1)) $((($y*50)+1)) "\\
	done
done
count from $(($i-1)) to 0 |
  while read j
  do
	for e in a b; do
		eval x=\$$e\x$j
		eval y=\$$e\y$j
#		echo "paste $i at ($x,$y)" 1>&2
		echo "	circle.$j $((($x*50)+2)) $((($y*50)+2)) "\\
	done
  done
echo ''
) | sh