p
q
1
r
r
=0 (mod 2)
or
p
=
r
= 1 (mod 2)
,
pq
1
r
=
r
1
qp
pq
1
r
2
3
4
5
6
2
2
3
2
4
2
5
2
6
2
pq
1
r
Tables
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