B. Hossam and Friendstime limit per test2 secondsmemory limit per test256 megabytesinputstandard inputoutputstandard outputHossam 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.InputThe 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.OutputFor each test case print an integer — the number of good subsegments.ExampleInput
23 21 32 34 21 22 3Output
4
5
NoteIn 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]
23 21 32 34 21 22 3
4 5 
['binary search', 'constructive algorithms', 'dp', 'two pointers', '*1400']