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