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, 15) :

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	12		15	1	0	0	1
1	12		15	1	0	0	1	3						6	16	12	8	6
2	6		15	8	6	0	1	9						3	Even	Even	4	3
3	3		15	4	3	0	1	12	1	4	4	4	4	6	Even	Even	2	2
4	6	↔	3	2	2	4	3	3						3	Even	Even	1	1
5	3	↔	3	1	1	4	3	0
6	3	↔	3	1	1	4	3	0
7	3		3	4	3	1	1	0
(4)(12) - (3)(15) = 3