I know I am missing something here but if you could help me I'd really appreciate it, especially if you could answer before Shabbos.

Rashi in megillah 30b when explaining the leining for chol hamoed Sukkos 5 lines form the bottom says

"Lefichoch Yom 7 shel Chol Hamoed"

but there is not such thing as the seventh day of Chol Hamoed!!!

Could you please enlighten me ? Are there any other editions which you may be aware of where it says something different etc. or am I just reading wrong?

Thank you in advance

Moshe Deutsch