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

