[0]:[0]
[1]:[1]
[2]:[2]
[3]:[3]
[4]:[4]
[5]:[5]
[6]:[6]
[7]:[7]
[8]:[8]
[9, 10]:[9]
[11]:[10]
[12]:[11, 12]
[13]:[13]
[14, 15]:[14, 15]
[16]:[16]
[17]:[17, 18]
[18]:[19, 20]
[19]:[21]
[20]:[22]
[21]:[23]
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[24]:[25]
[25]:[26]
[26]:[27, 28]
[27]:[29]
[28]:[30]
[29]:[31]
[30]:[32]
[31]:[33, 34]
[32]:[35]
[33]:[36]
[34]:[37]
[35]:[38]
[]:[39]