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

