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

