talk:>>24
20={0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19},
19={0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18},
18={0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17},
…
0={}.