Problem Statement

You are given a sequence of positive integers $A=(A_1,A_2,\dots,A_N)$ of length N and a positive integer K.
Find the sum of the integers between 1 and K, inclusive, that do not appear in the sequence A.

Input

The input is given from Standard Input in the following format:
N K
$A_1 A_2 \dots A_N$

Output

Print the answer.

Constraints

• $1\leq N \leq 2\times 10^5$
• $1\leq K \leq 2\times 10^9$
• $1\leq A_i \leq 2\times 10^9$
• All input values are integers.

Sample Input 1

4 5
1 6 3 1

Sample Output 1

11

Among the integers between 1 and 5, three numbers, 2, 4, and 5, do not appear in A.
Thus, print their sum: 2+4+5=11.

Sample Input 2

1 3
346

Sample Output 2

6

Sample Input 3

10 158260522
877914575 24979445 623690081 262703497 24979445 1822804784 1430302156 1161735902 923078537 1189330739

Sample Output 3

12523196466007058

见题面 Input 部分

见题面 Output 部分