flow.size: 8
row.1: 3,4,0,0,0,0,4,1
row.2: 0,0,3,0,0,0,8,0
row.3: 7,0,8,0,1,0,0,0
row.4: 2,0,0,5,0,0,0,0
row.5: 0,0,0,0,0,0,6,0
row.6: 9,2,6,0,0,7,0,0
row.7: 0,0,0,9,0,0,0,0
row.8: 5,0,0,0,0,0,0,0












