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, 14) :
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
14
1
0
0
1
1
14
↔
13
0
1
1
0
1
7
14
14
7
7
2
7
↔
13
7
7
1
0
6
1
8
7
8
7
3
22
20
11
10
3
3
7
11
10
7
7
4
1
18
17
4
4
2
Even
Even
2
2
4
2
↔
3
2
2
11
10
1
1
Even
Even
1
1
5
1
↔
3
1
1
11
10
2
1
12
11
12
11
1
26
24
13
12
6
1
1
13
12
1
1
0
7
1
1
13
12
1
1
0
(13)(13) - (12)(14) = 1