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

