8 6 10 4 18 14 2 16 12 20
7
x
2
=
4
x
2
=
9
x
2
=
6
x
2
=
3
x
2
=
8
x
2
=
10
x
2
=
1
x
2
=
2
x
2
=
5
x
2
=
0
x
2
=
0