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