\\           Y
\\      2   1
\\       \ /
\\     3--*--0 X
\\       / \
\\      4   5

dz = [1, I, I-1, -1, -I, 1-I]
z = 0
d = 0
n = -1

move(printonly=0) = {
	if (!printonly,
		z += dz[1+d%#dz];
	);
	print (n++ " " imag(z));
}

L(r) = {
	move();
}

F(r) = {
	if (r-->=0,
		F(r);
		d++;
		L(r);
		d++;
		F(r);
		d--;
		L(r);
		d--;
		F(r)
		,
		move()
	);
}

move(1)
F(7)

quit