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












