SOLVE
LATER
Consider the following game. There is a field with $$n$$ rows and $$3$$ columns. Some cells contain obstacles. But the first row is always empty. Let's define cell in $$i$$-th row and $$j$$-th column as $$(i, j)$$. From cell $$(i, j)$$ you can go to cells $$(i + 1, j - 1)$$, $$(i + 1, j)$$ and $$(i + 1, j + 1)$$ if such cell exists (you can't go out of field) and doesn't contain obstacle. You can start in any column in the first row. What is the maximum $$i$$, such that $$i$$-th row is reachable?
Input format
Given several test cases.
First line of input contains integer $$T$$ ($$1 \leq T \leq 3 \cdot 10^5$$) — number of test cases.
Then follow $$T$$ blocks of input.
The first line of block contains integers $$n$$ and $$q$$ ($$2 \leq n \leq 10^9$$, $$0 \leq q \leq \min(3 \cdot 10^5, 3 \cdot (n - 1))$$) — number of rows and number of obstacles, respectively.
Then follow $$q$$ lines with obstacles description.
The $$i$$-th of them contains integers $$x$$ and $$y$$ ($$2 \leq x \leq n$$, $$1 \leq y \leq 3$$) — the coordinates of $$i$$-th obstacle, located at $$(x, y)$$.
Coordinates of all obstacles in a single test case are pairwise distinct.
Sum of all $$q$$ in input doesn't exceed $$3 \cdot 10^5$$.
Output format
For each block print single integer — the maximum row that is possible to be reached.
In the first test case one of the optimal paths is $$(1, 2)$$, $$(2, 1)$$, $$(3, 2)$$, $$(4, 2)$$. So the row $$4$$ is possible to be reached.
In the second test case there are no possible moves from $$(1, 2)$$. So only the row $$1$$ is possible to be reached.