For each box sequence in the input file, output the length of the longest nesting string on one line followed on the next line by a list of the boxes that comprise this string in order.

对应输入的每个盒子序列，应在第一行输出最长的嵌套串长度，在下一行按顺序输入组成这个嵌套串的盒子列表。

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For each box sequence in the input file, output the length of the longest nesting string on one line followed on the next line by a list of the boxes that comprise this string in order.

对应输入的每个盒子序列，应在第一行输出最长的嵌套串长度，在下一行按顺序输入组成这个嵌套串的盒子列表。

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