C++ please. Very confused.

C++ code. Notice also the quotes in the program call, to avoid Unix/Windows getting confused. See part 4. 3. Input and Output The input and output files are regular text files, where each line is terminated with a In' character. Each line will be treated as a string. The output file will contain the length of the subsequence. Output format: ."Len:"+the length of the subsequence. Note, in "Len: ", there is a space after the colon (:) All records should be processed sequentially from beginning to end. Note that, input and output, all are case sensitive. Please, see examples to be clarified about the format