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