flow.size: 8
row.1: 2,0,2,0,0,0,0,5
row.2: 0,0,3,5,7,0,0,7
row.3: 0,0,0,4,6,0,3,0
row.4: 0,0,0,8,1,0,9,0
row.5: 0,0,0,0,0,0,0,0
row.6: 0,4,8,0,6,0,0,0
row.7: 0,1,0,0,9,0,0,0
row.8: 0,0,0,0,0,0,0,0

