101702: [AtCoder]ABC170 C - Forbidden List
Description
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.
Sample Input 1
6 5 4 7 10 6 5
Sample Output 1
8
Among the integers not contained in the sequence $4, 7, 10, 6, 5$, the one nearest to $6$ is $8$.
Sample Input 2
10 5 4 7 10 6 5
Sample Output 2
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, $9$.
Sample Input 3
100 0
Sample Output 3
100
When $N = 0$, the second line in the input will be empty. Also, as seen here, $X$ itself can be the answer.