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

