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

