line number field的意思|示意

If you omit the second number, sort will assume that the key starts at the given field and continues to the end of each line.

如果您省略了第二个数字，那么sort会假定键是从给定的字段开始，一直到每一行的末尾。

The desc field contains the line number and the value contains the code address for the start of that source line.

desc字段包含行号，而value包含源代码行的起始部分的代码地址。

Output will consist of one line for each triangle, containing the number of trees for that triangle right justified in a field of width 4.

每个输入的三角形对应一行输出，打印出在该三角形内部的树的数量。输出的数字应右对齐至第4列。