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

