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