big limit = 100 000
big values = Set([])
small values = vector(4, i, [])

see index(z) = {
	my (s=1, x=real(z), y=imag(z));
	if (x<1,
		s += 1;
		x = 1-x;
	);
	if (y<0,
		s += 2;
		y = -y;
	);
	return ([s,x,y]);
}

see(z) = {
	my (index = see index(z));
	if (max(index[2],index[3]) > big limit,
		big values = set union(big values, Set([z])),
		if (#small values[index[1]] < index[2],
			small values[index[1]] = concat(small values[index[1]], vector(index[2] - #small values[index[1]]))
		);
		small values[index[1]][index[2]] = bit or(small values[index[1]][index[2]], 2^index[3])
	);
}

seen(z) = {
	my (index = see index(z));
	if (max(index[2],index[3]) > big limit,
		return (set search(big values, z)),
		if (#small values[index[1]] < index[2],
			return (0),
			return (bit test(small values[index[1]][index[2]], index[3]))
		);
	);
}

neigbbours(z) = if (real(z)%2==imag(z)%2, [z-1, z+1, z-I], [z-1, z+1, z+I])

new neighbours(z) = {
	select(zz -> !seen(zz) && #select(seen, neigbbours(zz))==1, neigbbours(z))
}

allocate mem(2^30)

c = Set(0);
nb = 0;

{
	for (n=0, 10 000,
		print (n " " nb);
		nb += #c;
		for (i=1, #c,
			see(c[i]);
		);

		c = Set(concat(apply(new neighbours, c)))
	);
}

quit