#P1771B. Hossam and Friends
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ID: 8384
Type: RemoteJudge
2000ms
256MiB
Tried: 1
Accepted: 1
Difficulty: 10
Uploaded By:
Hydro
Tags> Hossam and Friends
Description
Hossam makes a big party, and he will invite his friends to the party.
He has $n$ friends numbered from $1$ to $n$. They will be arranged in a queue as follows: $1, 2, 3, \ldots, n$.
Hossam has a list of $m$ pairs of his friends that don't know each other. Any pair not present in this list are friends.
A subsegment of the queue starting from the friend $a$ and ending at the friend $b$ is $[a, a + 1, a + 2, \ldots, b]$. A subsegment of the queue is called good when all pairs of that segment are friends.
Hossam wants to know how many pairs $(a, b)$ there are ($1 \le a \le b \le n$), such that the subsegment starting from the friend $a$ and ending at the friend $b$ is good.
The input consists of multiple test cases. The first line contains a single integer $t$ ($1 \le t \le 2 \cdot 10^4$), the number of test cases. Description of the test cases follows.
The first line of each test case contains two integer numbers $n$ and $m$ ($2 \le n \le 10^5$, $0 \le m \le 10^5$) representing the number of friends and the number of pairs, respectively.
The $i$-th of the next $m$ lines contains two integers $x_i$ and $y_i$ ($1 \le x_i, y_i\le n$, $x_i \neq y_i$) representing a pair of Hossam's friends that don't know each other.
Note that pairs can be repeated.
It is guaranteed that the sum of $n$ over all test cases does not exceed $10^5$, and the sum of $m$ over all test cases does not exceed $10^5$.
For each test case print an integer — the number of good subsegments.
Input
The input consists of multiple test cases. The first line contains a single integer $t$ ($1 \le t \le 2 \cdot 10^4$), the number of test cases. Description of the test cases follows.
The first line of each test case contains two integer numbers $n$ and $m$ ($2 \le n \le 10^5$, $0 \le m \le 10^5$) representing the number of friends and the number of pairs, respectively.
The $i$-th of the next $m$ lines contains two integers $x_i$ and $y_i$ ($1 \le x_i, y_i\le n$, $x_i \neq y_i$) representing a pair of Hossam's friends that don't know each other.
Note that pairs can be repeated.
It is guaranteed that the sum of $n$ over all test cases does not exceed $10^5$, and the sum of $m$ over all test cases does not exceed $10^5$.
Output
For each test case print an integer — the number of good subsegments.
2
3 2
1 3
2 3
4 2
1 2
2 3
4
5
Note
In the first example, the answer is $4$.
The good subsegments are:
[1]
[2]
[3]
[1, 2]
In the second example, the answer is $5$.
The good subsegments are:
[1]
[2]
[3]
[4]
[3, 4]