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

