C - Forbidden List

Score : $300$ points

Problem Statement

Given are an integer $X$ and an integer sequence of length $N$: $p_1, \ldots, p_N$.

Among the integers not contained in the sequence $p_1, \ldots, p_N$ (not necessarily positive), find the integer nearest to $X$, that is, find the integer whose absolute difference with $X$ is the minimum. If there are multiple such integers, report the smallest such integer.

Constraints

• $1 \leq X \leq 100$
• $0 \leq N \leq 100$
• $1 \leq p_i \leq 100$
• $p_1, \ldots, p_N$ are all distinct.
• All values in input are integers.

Input

Input is given from Standard Input in the following format:

$X$ $N$

$p_1$ $...$ $p_N$

Output

Print the answer.

6 5
4 7 10 6 5

8

Among the integers not contained in the sequence $4, 7, 10, 6, 5$, the one nearest to $6$ is $8$.

10 5
4 7 10 6 5

9

Among the integers not contained in the sequence $4, 7, 10, 6, 5$, the ones nearest to $10$ are $9$ and $11$. We should print the smaller one, $9$.

100 0

100

When $N = 0$, the second line in the input will be empty. Also, as seen here, $X$ itself can be the answer.