Count the Holidays

A particular month has $30$ days, numbered from $1$ to $30$. Day $1$ is a Monday, and the usual $7$-day week is followed (so day $2$ is Tuesday, day $3$ is Wednesday, and so on). Every Saturday and Sunday is a holiday. There are $N$ festival days, which are also holidays. Note that it is possible for a festival day to occur on a Saturday or Sunday. You are given the dates of the festivals. Dete