|1x3 Cross validator
2, 2, 1, 2, 2.
2, 1, 1, 2, 2.
1, 1, 2, 1, 3.
2, 2, 1, 1, 3.
1, 1, 2, 2, 1.
3, 2, 1, 1, 3.
1, 2, 2, 2, 1.
1, 1, 1, 2, 2.