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

