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

