X =	00	01	02	03	04	05	06	07	08	09	10	11	12	13	14	15
Y =	00	01	02	03	04	05	06	07	08	09	10	11	12	13	14	15
X ↔ Y

Ext-GCD(12, 6) → Twos = 1 → Ext-GCD(6, 3) :

i	GCD			Bezout				AOdd :						AEven :
	A	↔	B	ax	ay	bx	by	|A-B|	A↔B	Sx	Sy	ax ← Sx'	ay ← Sy'	A ← A/2	ax ← ax + Y	ay ← ay + X	ax ← ax/2	ay ← ay/2
0	6		3	1	0	0	1
1	6		3	1	0	0	1	3						3	4	6	2	3
2	3		3	2	3	0	1	0
3	3		3	2	3	0	1	0
4	3		3	2	3	0	1	0
5	3		3	2	3	0	1	0
6	3		3	2	3	0	1	0
7	3		3	2	3	0	1	0
(2)(12) - (3)(6) = 6