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