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