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

