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