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

