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

