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