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