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(11, 12) :
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
11
12
1
0
0
1
1
12
↔
11
0
1
1
0
1
6
12
12
6
6
2
6
↔
11
6
6
1
0
5
3
Even
Even
3
3
3
3
↔
11
3
3
1
0
8
1
4
3
4
3
4
16
14
8
7
4
4
3
8
7
3
3
1
2
20
18
10
9
5
2
3
10
9
3
3
1
1
22
20
11
10
6
1
3
11
10
3
3
2
1
14
13
2
2
1
Even
Even
1
1
7
1
1
11
10
1
1
0
(11)(11) - (10)(12) = 1