Clarifications:
1. Commands are case-sensitive.
2. \"" is a command and a quote.
3. \"j is a command and a letter j.

Tips:
1. Don't process the \endinput command. Although it's said to terminate the input, something else may follow. Use 'repeat until eof' (not seekeof!!) to judge the EOF.
2. Don't forget to clear the unmatched quote when you reach EOF.