column must include all digits
from 1 through n in any order 1 2 2 1 1 2 3 2 3 1 3 1 2 1 2 3 4 4 3 2 1 2 1 4 3 3 4 1 2 1 2 3 4 5 4 5 1 2 3 2 3 4 5 1 5 1 2 3 4 3 4 5 1 2 1 2 3 4 5 6 2 3 4 5 6 1 3 4 5 6 1 2 4 5 6 1 2 3 5 6 1 2 3 4 6 1 2 3 4 5 1 2 3 4 5 6 7 5 6 7 1 2 3 4 2 3 4 5 6 7 1 6 7 1 2 3 4 5 3 4 5 6 7 1 2 7 1 2 3 4 5 6 4 5 6 7 1 2 3 23-04-2006