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On Penacony, The Land of the Dreams, there exists $n$ houses and $n$ roads. There exists a road between house $i$ and $i+1$ for all $1 \leq i \leq n-1$ and a road between house $n$ and house $1$. All roads are bidirectional. However, due to the crisis on Penacony, the overseeing family has gone into debt and may not be able to maintain all roads. There are $m$ pairs of friendships between the residents of Penacony. If the resident living in house $a$ is friends with the resident living in house $b$, there must be a path between houses $a$ and $b$ through maintained roads. What is the minimum number of roads that must be maintained? The first line contains $t$ ($1 \leq t \leq 10^4$) – the number of test cases. The first line of each test case contains two integers $n$ and $m$ ($3 \leq n \leq 2 \cdot 10^5, 1 \leq m \leq 2 \cdot 10^5$) – the number of houses and the number of friendships. The next $m$ lines contain two integers $a$ and $b$ ($1 \leq a < b \leq n$) – the resident in house $a$ is friends with the resident in house $b$. It is guaranteed all ($a, b$) are distinct. It is guaranteed the sum of $n$ and $m$ over all test cases does not exceed $2 \cdot 10^5$. For each test case, output an integer, the minimum number of roads that must be maintained. For the first test case, the following roads must be maintained: * $8 \leftarrow \rightarrow 1$ * $7 \leftarrow \rightarrow 8$ * $1 \leftarrow \rightarrow 2$ * $4 \leftarrow \rightarrow 5$ |