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

