Problem:
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.

Solution in JavaScript (Node.js 12.16.1) (judge verdict: Accepted)

const main = (input) => {
  const args = input.trim().split("\n");
  const [x, n] = args[0]
    .trim()
    .split(" ")
    .map((n) => parseInt(n, 10));
 
  const excluded = (() => {
    if (n === 0) {
      return [];
    } else {
      return args[1]
        .trim()
        .split(" ")
        .map((n) => parseInt(n, 10));
    }
  })();
 
  const selection = [...Array(101 + 1).keys()].filter(
    (s) => !excluded.includes(s)
  );
 
  const abs = (n) => {
    if (n < 0) return -n;
    else {
      return n;
    }
  };
  const byAsc = (a, b) => a[1] - b[1];
 
  const answer = selection
    .map((s) => [s, abs(x - s)])
    .sort(byAsc)[0][0];
 
  console.log(answer);
};
 
main(require("fs").readFileSync("/dev/stdin", "utf8"));