Solve the programming task below in a Python markdown code block.
Read problems statements in [Hindi], [Mandarin Chinese], [Russian], [Vietnamese] and [Bengali] as well.

You have $C = 100,000$ cakes, numbered $1$ through $C$. Each cake has an integer height; initially, the height of each cake is $0$.

There are $N$ operations. In each operation, you are given two integers $L$ and $R$, and you should increase by $1$ the height of each of the cakes $L, L+1, \ldots, R$. One of these $N$ operations should be removed and the remaining $N-1$ operations are then performed.

Chef wants to remove one operation in such a way that after the remaining $N-1$ operations are performed, the number of cakes with height exactly $K$ is maximum possible. Since Chef is a bit busy these days, he has asked for your help. You need to find the maximum number of cakes with height exactly $K$ that can be achieved by removing one operation.

------  Input ------
The first line of the input contains a single integer $T$ denoting the number of test cases. The description of $T$ test cases follows.
The first line of each test case contains two space-separated integers $N$ and $K$.
Each of the next $N$ lines contains two space-separated integers $L$ and $R$ describing one operation.

------  Output ------
For each test case, print a single line containing one integer — the maximum possible number of cakes with height $K$.

------  Constraints  ------
$1 ≤ T ≤ 100$
$2 ≤ N ≤ 10^{5}$
$1 ≤ K ≤ N$
$1 ≤ L ≤ R ≤ 10^{5}$
the sum of $N$ over all test cases does not exceed $10^{6}$

----- Sample Input 1 ------ 
1
3 2
2 6
4 9
1 4
----- Sample Output 1 ------ 
3
----- explanation 1 ------ 
Example case 1: Let's look at what happens after an operation is removed.
- Removing operation $1$: The heights of cakes $4$ through $9$ increase by $1$. Then, the heights of cakes $1$ through $4$ increase by $1$. The resulting sequence of heights is $[1, 1, 1, 2, 1, 1, 1, 1, 1]$ (for cakes $1$ through $9$; the other cakes have heights $0$). The number of cakes with height $2$ is $1$.
- Removing operation $2$: The resulting sequence of heights of cakes $1$ through $9$ is $[1, 2, 2, 2, 1, 1, 0, 0, 0]$. The number of cakes with height $2$ is $3$.
- Removing operation $3$: The resulting sequence of heights of cakes $1$ through $9$ is $[0, 1, 1, 2, 2, 2, 1, 1, 1]$. The number of cakes with height $2$ is $3$.

The maximum number of cakes with height $2$ is $3$.