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(6, 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
6
13
1
0
0
1
1
6
13
1
0
0
1
7
3
14
6
7
3
2
3
13
7
3
0
1
10
1
7
4
7
4
5
20
10
10
5
3
5
↔
3
10
5
7
3
2
0
17
8
4
2
1
Even
Even
2
1
4
1
↔
3
2
1
7
3
2
1
9
4
9
4
1
22
10
11
5
5
1
1
11
5
2
1
0
6
1
1
11
5
2
1
0
7
1
1
11
5
2
1
0
(11)(6) - (5)(13) = 1