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(9, 8) :
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
9
8
1
0
0
1
1
8
↔
9
0
1
1
0
1
4
8
10
4
5
2
4
↔
9
4
5
1
0
5
2
12
14
6
7
3
2
↔
9
6
7
1
0
7
1
14
16
7
8
4
1
↔
9
7
8
1
0
8
1
8
8
8
8
4
Even
Even
4
4
5
4
1
4
4
7
8
3
2
Even
Even
2
2
6
2
1
2
2
7
8
1
1
Even
Even
1
1
7
1
1
1
1
7
8
0
(1)(9) - (1)(8) = 1