Problem Statement

Given are integer sequences of length N each: $A = (A_1, \dots, A_N)$ and $C = (C_1, \dots, C_N)$.
You can do the following operation any number of times, possibly zero.

• Choose an integer i such that $1 \leq i \leq N$ and add 1 to the value of A_i, for a cost of C_i yen (Japanese currency).

After you are done with the operation, you have to pay $K \times X$ yen, where K is the number of different values among the elements of A.
What is the minimum total amount of money you have to pay?

Input

Input is given from Standard Input in the following format:
N X
A_1 C_1
$\vdots$
A_N C_N

Output

Print a number representing the answer.

Constraints

• $1 \leq N \leq 2 \times 10^5$
• $1 \leq X \leq 10^6$
• $1 \leq A_i, C_i \leq 10^6$ $, (1 \leq i \leq N)$
• All values in input are integers.

Sample Input 1

3 5
3 2
2 4
4 3

Sample Output 1

12

After adding 1 to A_1, there will be two different values among the elements of A, for a total cost of $C_1 + 2 \times X = 12$ yen. It is impossible to make the total cost less than this.

Sample Input 2

1 1
1 1

Sample Output 2

1

Sample Input 3

7 7
3 2
1 7
4 1
1 8
5 2
9 8
2 1

Sample Output 3

29

见题面 Input 部分

见题面 Output 部分