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

