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












