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