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