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(14, 15) :
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
14
15
1
0
0
1
1
14
15
1
0
0
1
1
7
16
14
8
7
2
7
15
8
7
0
1
8
1
8
8
8
8
4
Even
Even
4
4
3
4
↔
7
4
4
8
7
3
2
Even
Even
2
2
4
2
↔
7
2
2
8
7
5
1
Even
Even
1
1
5
1
↔
7
1
1
8
7
6
1
9
8
9
8
3
24
22
12
11
6
3
1
12
11
1
1
2
0
13
12
13
12
1
28
26
14
13
7
1
1
14
13
1
1
0
(14)(14) - (13)(15) = 1