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

