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(13, 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
13
11
1
0
0
1
1
13
11
1
0
0
1
2
0
1
1
1
1
1
12
14
6
7
2
1
11
6
7
0
1
10
1
6
8
6
8
5
Even
Even
3
4
3
5
↔
1
3
4
6
7
4
0
9
11
9
11
2
20
24
10
12
4
2
↔
1
10
12
6
7
1
1
Even
Even
5
6
5
1
↔
1
5
6
6
7
0
6
1
↔
1
5
6
6
7
0
7
1
1
6
7
5
6
0
(6)(13) - (7)(11) = 1