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