file line length的意思|示意

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。

The output file should contain a single line with a single integer that represents the length of the longest theme.

输出文件应只含一个整数，即最长主题的长度。

To get the length of each line in the file text, use the length function.

若要获取文件中每行文本的长度，请使用length函数。