flow.size: 8
row.1: 0,2,9,0,3,1,0,0
row.2: 0,0,0,0,7,5,0,0
row.3: 0,0,7,3,0,6,0,1
row.4: 0,0,0,0,0,0,0,8
row.5: 0,9,0,0,0,0,5,0
row.6: 0,6,0,0,0,0,2,0
row.7: 0,0,0,0,4,0,4,0
row.8: 8,0,0,0,0,0,0,0