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

