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)

function main(input) {
  let args = input.split('\n');
  let a = 0;
  let [x, n] = args[a++].split(' ').map((e) => +e);
  if (n == 0) {
    console.log(x);
    return;
  }
  let arr = args[a++].split(' ');
  let map = {};
  for (let i = 0; i < n; ++i) {
    const e = +arr[i];
    if (!map[e]) {
      map[e] = 1;
    }
  }
  let min = null;
  let max = null;
  for (let i = x; x > -1; --i) {
    if (!map[i]) {
      min = i;
      break;
    }
  }
  for (let i = x; x < 101; ++i) {
    if (!map[i]) {
      max = i;
      break;
    }
  }
  let diffA = x - min;
  let diffB = max - x;
  if (diffA == diffB) {
    console.log(Math.min(min, max));
  } else if (diffA < diffB) {
    console.log(min);
  } else {
    console.log(max);
  }
}

main(require('fs').readFileSync('/dev/stdin', 'utf8'));