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