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]))
		);
	);
}

a = vector(2500)
u = 0
see(a[u++] = 0)
print (u " " imag(a[u]))

{
	for (n=1, #a,
		z0 = a[n];
		for (k=1, oo,
			if (!#select(d -> seen(z0+k*I^d), [0..3]),
				for (d=0, 3,
					my (z=z0+k*I^d);
					see(z);
					print (u++ " " imag(z));
					if (u<=#a,
						a[u] = z;
					);
				);
				break;
			);
		);
	);
}

quit