A cinema has n rows of seats, numbered from $1$ to n, with $10$ seats in each row numbered from $1$ to $10$.

You are given the integer n and a $2$D integer array reservedSeats, where reservedSeats[i] = [row, col] indicates that the seat at row row and column col is already reserved.

A four person family requires four adjacent seats in the same row. Seats separated by aisles (between seats $3$ and $4$, and between seats $7$ and $8$) are not considered adjacent. Consequently, the only valid configurations for a four person family are:

• Seats $2$, $3$, $4$, and $5$

• Seats $4$, $5$, $6$, and $7$

• Seats $6$, $7$, $8$, and $9$

Return the maximum number of four person families you can seat in the cinema.

Note: A single row can seat at most $2$ families (specifically, one in seats $2$, $3$, $4$, $5$ and one in seats $6$, $7$, $8$, $9$).

Constraints:

• $1 \leq$ n $\leq 10^9$

• $1 \leq$ reservedSeats.length $\leq \min(10 \cdot$ n$, 10^4)$

• reservedSeats[i].length $= 2$

• $1 \leq$ reservedSeats[i][0] $\leq$ n

• $1 \leq$ reservedSeats[i][1] $\leq 10$

• All reservedSeats[i] are distinct.

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