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

